Re: [PATCH] Use current_inferior ()->pid for AIX

Re: [PATCH] Use current_inferior ()->pid for AIX

[Ulrich Weigand]

Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com> wrote:

>AIX is still using inferior_ptid.pid() to get the inferior pid instead
>of the new object current_inferior().With this it is not possible to
>debug any sample program as the it fails with assertion check for
>pid!=0.

I don't quite understand the underlying problem here.  While we may
want to get rid of inferior_ptid at some point in the future, as of
right now inferior_ptid *is* still being used (by many places in the
target stack), and should always be maintained correctly.

Maybe the problem is really that somewhere inferior_ptid isn't being
updated as it should?


As an aside, this part changes semantics of the code:

>@@ -932,11 +932,12 @@
> static void
> pd_deactivate (void)
> {
>+  ptid_t ptdrtn = ptid_t (current_inferior ()->pid);
>   if (!pd_active)
>     return;
>   pthdb_session_destroy (pd_session);
>   
>-  pid_to_prc (&inferior_ptid);
>+  pid_to_prc (&ptdrtn); 
>   pd_active = 0;
> }

The point of this code was to *change* inferior_ptid back from
the per-thread view to the no-threads view as the threading
layer is deactivated.  With your patch, inferior_ptid is no
longer changed at all, which makes the pid_to_prc call useless.

Bye,
Ulrich

[PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

[-- Attachment #1: Type: text/plain, Size: 2903 bytes --]

Hi all,



Attaching the patch for fetching the inferior process ID using current_inferior() function in AIX.



AIX is still using inferior_ptid.pid() to get the inferior pid instead of the new object current_inferior().With this it is not possible to debug any sample program as the it fails with assertion check for pid!=0.

In the gdb to access the process id of the debugged inferior process, a function current_inferior is used which returns the struct type variable inferior. As current_inferior() holds the inferior pid one must use this object to hold the inferior pid. The attached patch is to the current_inferior() object to get the inferior pid and continue debugging.



This can be demonstrated using the below sample program.



#include <stdio.h>

#include <stdlib.h>

int main()

{

   int i = 1;

   return 0;

}



Sample output without patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e874a3 ???

0x100e8766b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa5b ???

0x1002f6e37 ???

0x1002f2e7f ???

0x100b26ca3 ???

0x1003029bf ???

0x10077e373 ???

0x10077b107 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.



Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;



----------------------------------------------------------------------------------



Summary of the gdb.base testsuites.



Without Patch
------------------------

# of expected passes

8096

# of unexpected failures

2160

# of unexpected successes

1

# of expected failures

4

# of known failures

5

# of unresolved testcases

113

# of untested testcases

83

# of unsupported tests

40

# of paths in test names

2

# of duplicate test names

13

With Patch
-------------------

# of expected passes

13831

# of unexpected failures

7397

# of unexpected successes

1

# of expected failures

11

# of known failures

6

# of unresolved testcases

78

# of untested testcases

88

# of unsupported tests

63

# of paths in test names

1

# of duplicate test names

2

(See attached file: ChangeLog)(See attached file: current_inferior.patch).



Thanks and regards,

Aditya.


[-- Attachment #2: ChangeLog --]
[-- Type: application/octet-stream, Size: 386 bytes --]

2022-03-15  Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>

	*aix-thread.c (get_signaled_thread): Use current_inferior->pid() instead of
	inferior_ptid.pid() in AIX.
	(sync_threadlists): Likewise.
	(pd_update) : Likewise.
	(pd_activate): Likewise.
	(pd_deactivate): Likewise.
	*rs6000-aix-nat.c (xfer_partial): Likewise.
	(wait): Likewise.
	(xfer_shared_libraries): Likewise.

[-- Attachment #3: current_inferior.patch --]
[-- Type: application/octet-stream, Size: 2806 bytes --]

--- ./gdb/aix-thread.c_orig	2022-03-15 02:26:39 +0000
+++ ./gdb/aix-thread.c	2022-03-03 07:21:16 +0000
@@ -708,7 +708,7 @@
 
   while (1)
     {
-      if (getthrds (inferior_ptid.pid (), &thrinf,
+      if (getthrds ( current_inferior ()->pid, &thrinf,
 		    sizeof (thrinf), &ktid, 1) != 1)
 	break;
 
@@ -791,7 +791,7 @@
 
   /* Apply differences between the two arrays to GDB's thread list.  */
 
-  infpid = inferior_ptid.pid ();
+  infpid = current_inferior ()->pid;
   for (pi = gi = 0; pi < pcount || gi < gcount;)
     {
       if (pi == pcount)
@@ -883,11 +883,11 @@
   struct thread_info *thread = NULL;
 
   if (!pd_active)
-    return inferior_ptid;
+    return ptid_t (current_inferior ()->pid);
 
   status = pthdb_session_update (pd_session);
   if (status != PTHDB_SUCCESS)
-    return inferior_ptid;
+   return ptid_t (current_inferior ()->pid);
 
   sync_threadlists ();
 
@@ -897,7 +897,7 @@
   if (tid != 0)
     thread = iterate_over_threads (iter_tid, &tid);
   if (!thread)
-    ptid = inferior_ptid;
+    ptid = ptid_t (current_inferior ()->pid); 
   else
     {
       ptid = thread->ptid;
@@ -921,7 +921,7 @@
 			       &pd_session);
   if (status != PTHDB_SUCCESS)
     {
-      return inferior_ptid;
+      return ptid_t (current_inferior ()->pid);
     }
   pd_active = 1;
   return pd_update (set_infpid);
@@ -932,11 +932,12 @@
 static void
 pd_deactivate (void)
 {
+  ptid_t ptdrtn = ptid_t (current_inferior ()->pid);
   if (!pd_active)
     return;
   pthdb_session_destroy (pd_session);
   
-  pid_to_prc (&inferior_ptid);
+  pid_to_prc (&ptdrtn); 
   pd_active = 0;
 }
 
--- gdb/rs6000-aix-nat.c_orig	2022-03-15 02:27:22 +0000
+++ gdb/rs6000-aix-nat.c	2022-03-11 05:37:57 +0000
@@ -397,7 +397,7 @@
 				 ULONGEST offset, ULONGEST len,
 				 ULONGEST *xfered_len)
 {
-  pid_t pid = inferior_ptid.pid ();
+  pid_t pid =  current_inferior ()->pid;
   int arch64 = ARCH64 ();
 
   switch (object)
@@ -525,15 +525,14 @@
 
 	  /* Claim it exited with unknown signal.  */
 	  ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
-	  return inferior_ptid;
+	  return ptid_t (current_inferior ()->pid);
 	}
 
       /* Ignore terminated detached child processes.  */
-      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
+      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
 	pid = -1;
     }
   while (pid == -1);
   /* AIX has a couple of strange returns from wait().  */
 
   /* stop after load" status.  */
@@ -658,7 +657,7 @@
   if (writebuf)
     return TARGET_XFER_E_IO;
 
-  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
+   gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t (current_inferior ()->pid)); 
   result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
 				      readbuf, offset, len, 1);
 

Re: [PATCH] Use current_inferior ()->pid for AIX

[Simon Marchi]

On 2022-03-29 02:58, Aditya Vidyadhar Kamath via Gdb-patches wrote:
> Hi all,
> 
> 
> 
> Attaching the patch for fetching the inferior process ID using current_inferior() function in AIX.

Hi,

I am unable to apply the patch using git-am.  Can you send it using "git send-email" (ideally), or as
a fallback, generate it using "git format-patch" and attach it?

Thanks,

Simon

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

[-- Attachment #1: Type: text/plain, Size: 820 bytes --]

Hi,

Please find attached the patch.

Thanks,
Aditya.
________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Tuesday, March 29, 2022 6:31 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX



On 2022-03-29 02:58, Aditya Vidyadhar Kamath via Gdb-patches wrote:
> Hi all,
>
>
>
> Attaching the patch for fetching the inferior process ID using current_inferior() function in AIX.

Hi,

I am unable to apply the patch using git-am.  Can you send it using "git send-email" (ideally), or as
a fallback, generate it using "git format-patch" and attach it?

Thanks,

Simon

[-- Attachment #2: 0001-Use-current_inferior-pid-for-AIX.patch --]
[-- Type: application/octet-stream, Size: 3522 bytes --]

From eb10e0ebc422d01f5ce96786f0bcf78a4f57d7ef Mon Sep 17 00:00:00 2001
From: Aditya Vidyadhar Kamath
 <adityakamath@li-ee942a4f-4ab2-47e9-8494-fb53eafbb9e1.ibm.com>
Date: Wed, 30 Mar 2022 11:19:14 +0530
Subject: [PATCH] Use current_inferior ()->pid for AIX.

---
 gdb/aix-thread.c     | 15 ++++++++-------
 gdb/rs6000-aix-nat.c |  8 ++++----
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index 85be4c15f1c..9331de3beb2 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -708,7 +708,7 @@ get_signaled_thread (void)
 
   while (1)
     {
-      if (getthrds (inferior_ptid.pid (), &thrinf,
+      if (getthrds (current_inferior ()->pid, &thrinf,
 		    sizeof (thrinf), &ktid, 1) != 1)
 	break;
 
@@ -791,7 +791,7 @@ sync_threadlists (void)
 
   /* Apply differences between the two arrays to GDB's thread list.  */
 
-  infpid = inferior_ptid.pid ();
+  infpid = current_inferior ()->pid;
   for (pi = gi = 0; pi < pcount || gi < gcount;)
     {
       if (pi == pcount)
@@ -883,11 +883,11 @@ pd_update (int set_infpid)
   struct thread_info *thread = NULL;
 
   if (!pd_active)
-    return inferior_ptid;
+    return ptid_t (current_inferior ()->pid);
 
   status = pthdb_session_update (pd_session);
   if (status != PTHDB_SUCCESS)
-    return inferior_ptid;
+    return ptid_t (current_inferior ()->pid);
 
   sync_threadlists ();
 
@@ -897,7 +897,7 @@ pd_update (int set_infpid)
   if (tid != 0)
     thread = iterate_over_threads (iter_tid, &tid);
   if (!thread)
-    ptid = inferior_ptid;
+    ptid = ptid_t (current_inferior ()->pid);
   else
     {
       ptid = thread->ptid;
@@ -921,7 +921,7 @@ pd_activate (int set_infpid)
 			       &pd_session);
   if (status != PTHDB_SUCCESS)
     {
-      return inferior_ptid;
+      return ptid_t (current_inferior ()->pid);
     }
   pd_active = 1;
   return pd_update (set_infpid);
@@ -932,11 +932,12 @@ pd_activate (int set_infpid)
 static void
 pd_deactivate (void)
 {
+  ptid_t ptdrtn = ptid_t (current_inferior ()->pid)	
   if (!pd_active)
     return;
   pthdb_session_destroy (pd_session);
   
-  pid_to_prc (&inferior_ptid);
+  pid_to_prc (&ptdrtn);
   pd_active = 0;
 }
 
diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
index 8563aea313a..0b8e4d2c687 100644
--- a/gdb/rs6000-aix-nat.c
+++ b/gdb/rs6000-aix-nat.c
@@ -397,7 +397,7 @@ rs6000_nat_target::xfer_partial (enum target_object object,
 				 ULONGEST offset, ULONGEST len,
 				 ULONGEST *xfered_len)
 {
-  pid_t pid = inferior_ptid.pid ();
+  pid_t pid = current_inferior ()->pid;
   int arch64 = ARCH64 ();
 
   switch (object)
@@ -525,11 +525,11 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
 
 	  /* Claim it exited with unknown signal.  */
 	  ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
-	  return inferior_ptid;
+	  return ptid_t (current_inferior ()->pid);
 	}
 
       /* Ignore terminated detached child processes.  */
-      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
+      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
 	pid = -1;
     }
   while (pid == -1);
@@ -658,7 +658,7 @@ rs6000_nat_target::xfer_shared_libraries
   if (writebuf)
     return TARGET_XFER_E_IO;
 
-  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
+  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t(current_inferior ()->pid));
   result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
 				      readbuf, offset, len, 1);
 
-- 
2.27.0

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

Any updates in regards to this?

Thanks.
________________________________
From: Gdb-patches <gdb-patches-bounces+aditya.vidyadhar.kamath=ibm.com@sourceware.org> on behalf of Aditya Vidyadhar Kamath via Gdb-patches <gdb-patches@sourceware.org>
Sent: Wednesday, March 30, 2022 6:34 PM
To: Simon Marchi <simon.marchi@polymtl.ca>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi,

Please find attached the patch.

Thanks,
Aditya.
________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Tuesday, March 29, 2022 6:31 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX



On 2022-03-29 02:58, Aditya Vidyadhar Kamath via Gdb-patches wrote:
> Hi all,
>
>
>
> Attaching the patch for fetching the inferior process ID using current_inferior() function in AIX.

Hi,

I am unable to apply the patch using git-am.  Can you send it using "git send-email" (ideally), or as
a fallback, generate it using "git format-patch" and attach it?

Thanks,

Simon

Re: [PATCH] Use current_inferior ()->pid for AIX

[Simon Marchi]

Hi Aditya,

I don't think that using current_inferior throughout is a good solution
to your problems.  It will be case by case, unfortunately there's no
easy way out of this but to dig in GDB and understand its internals a
bit.

> From eb10e0ebc422d01f5ce96786f0bcf78a4f57d7ef Mon Sep 17 00:00:00 2001
> From: Aditya Vidyadhar Kamath
>  <adityakamath@li-ee942a4f-4ab2-47e9-8494-fb53eafbb9e1.ibm.com>
> Date: Wed, 30 Mar 2022 11:19:14 +0530
> Subject: [PATCH] Use current_inferior ()->pid for AIX.
> 
> ---
>  gdb/aix-thread.c     | 15 ++++++++-------
>  gdb/rs6000-aix-nat.c |  8 ++++----
>  2 files changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
> index 85be4c15f1c..9331de3beb2 100644
> --- a/gdb/aix-thread.c
> +++ b/gdb/aix-thread.c
> @@ -708,7 +708,7 @@ get_signaled_thread (void)
>  
>    while (1)
>      {
> -      if (getthrds (inferior_ptid.pid (), &thrinf,
> +      if (getthrds (current_inferior ()->pid, &thrinf,
>  		    sizeof (thrinf), &ktid, 1) != 1)

This function doesn't seem to depend on the current inferior/thread, so
it could easily be changed to receive the pid as a parameter.

>  	break;
>  
> @@ -791,7 +791,7 @@ sync_threadlists (void)
>  
>    /* Apply differences between the two arrays to GDB's thread list.  */
>  
> -  infpid = inferior_ptid.pid ();
> +  infpid = current_inferior ()->pid;
>    for (pi = gi = 0; pi < pcount || gi < gcount;)
>      {
>        if (pi == pcount)
> @@ -883,11 +883,11 @@ pd_update (int set_infpid)
>    struct thread_info *thread = NULL;
>  
>    if (!pd_active)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);
>  
>    status = pthdb_session_update (pd_session);
>    if (status != PTHDB_SUCCESS)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);

Here, the pd_update function seems to want to return the event ptid
unmodified.  So, perhaps that ptid could be passed by the caller and
returned here.  Or, pd_update could be changed to return an
optional<ptid_t> and the caller deals with returning the right ptid.

>  
>    sync_threadlists ();
>  
> @@ -897,7 +897,7 @@ pd_update (int set_infpid)
>    if (tid != 0)
>      thread = iterate_over_threads (iter_tid, &tid);
>    if (!thread)
> -    ptid = inferior_ptid;
> +    ptid = ptid_t (current_inferior ()->pid);
>    else
>      {
>        ptid = thread->ptid;
> @@ -921,7 +921,7 @@ pd_activate (int set_infpid)
>  			       &pd_session);
>    if (status != PTHDB_SUCCESS)
>      {
> -      return inferior_ptid;
> +      return ptid_t (current_inferior ()->pid);

This is the same idea as in pd_update.

>      }
>    pd_active = 1;
>    return pd_update (set_infpid);
> @@ -932,11 +932,12 @@ pd_activate (int set_infpid)
>  static void
>  pd_deactivate (void)
>  {
> +  ptid_t ptdrtn = ptid_t (current_inferior ()->pid)	
>    if (!pd_active)
>      return;
>    pthdb_session_destroy (pd_session);
>    
> -  pid_to_prc (&inferior_ptid);
> +  pid_to_prc (&ptdrtn);

Since pid_to_prc only writes to ptdrtn, it essentially a no-op.  I would
try just removing that call.  It was used to modify inferior_ptid after
the thread layer was disabled, which does not seem useful to me.

> diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
> index 8563aea313a..0b8e4d2c687 100644
> --- a/gdb/rs6000-aix-nat.c
> +++ b/gdb/rs6000-aix-nat.c
> @@ -397,7 +397,7 @@ rs6000_nat_target::xfer_partial (enum target_object object,
>  				 ULONGEST offset, ULONGEST len,
>  				 ULONGEST *xfered_len)
>  {
> -  pid_t pid = inferior_ptid.pid ();
> +  pid_t pid = current_inferior ()->pid;
>    int arch64 = ARCH64 ();
>  
>    switch (object)

Here, inferior_ptid should be valid, this change should not be
necessary.

> @@ -525,11 +525,11 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>  
>  	  /* Claim it exited with unknown signal.  */
>  	  ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
> -	  return inferior_ptid;
> +	  return ptid_t (current_inferior ()->pid);
>  	}
>  
>        /* Ignore terminated detached child processes.  */
> -      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
> +      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
>  	pid = -1;
>      }
>    while (pid == -1);

The target_ops::wait method implemenattions should ne rely on the
current inferior either.  I don't think that this target supports
debugging multiple processes at the same time, but imagine that it does,
eventually.  When rs6000_nat_target::wait gets called, the current
inferior is one of the inferiors managed by that target, at random.  So
what the wait method needs to do is fetch an event from the OS, and
returning, regardless of which inferior it applies to (except if a ptid
argument is given).  So, you should never need to use either
inferior_ptid nor current_inferior in wait.

> @@ -658,7 +658,7 @@ rs6000_nat_target::xfer_shared_libraries
>    if (writebuf)
>      return TARGET_XFER_E_IO;
>  
> -  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
> +  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t(current_inferior ()->pid));
>    result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
>  				      readbuf, offset, len, 1);

This is used by xfer_partial, where inferior_ptid should be valid, so
this change shouldn't be necessary.

Simon

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

[-- Attachment #1: Type: text/plain, Size: 11480 bytes --]

Hi,

A case by case analysis as suggested by you the last time has been done.

While the child process [the program to be debugged] is running inferior_ptid.pid() will not contain the child process ID. One has to use pid_t(current_inferior ()->pid) inorder to get the child process in AIX. GDB may allow you to execute many programmes at the same time. Numerous threads of execution can be initiated from multiple executables in each of multiple processes.

GDB uses an inferior object to represent the status of each programme run. An inferior usually correlates to a process, although it is more broad and may be used to targets without processes as well. Inferiors can be produced before a process runs and kept after it has completed. Inferiors have their own unique IDs, which are not the same as process ids. Each inferior may have several threads going through it. As a result, inferior ptid.pid may not need to contain the current inferior thread id. To obtain the inferior process ID, we must utilise current inferior()->pid in particular areas.

When the child process's pd_active variable is not set i.e. the process is not active one has to use the pid_t(current_inferior ()->pid) instead of inferior_ptid.pid() in AIX.

This can be demonstrated by the following code:


#include <stdio.h>

#include <stdlib.h>

int main()

{

   int i = 1;

   return 0;

}

Sample output without patch changes only in aix-thread.c at line 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Sample output with patch changes in aix-thread.c and without patch changes in rs6000-aix-nat.c:


Child process unexpectedly missing: There are no child processes..

Program terminated with signal ?, Unknown signal.

The program no longer exists.

Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;


-------------------------------------------

When there are multiple threads running in a debugging process, inferior_ptid will not have the exact current inferior thread. Instead we need to use ptid_t (current_inferior ()->pid) to get it in AIX.


This can be shown by the following program:


#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <pthread.h>

#include <assert.h>

pthread_barrier_t barrier;

#define NUM_THREADS 2

void *

thread_function (void *arg)

{

pthread_barrier_wait (&barrier);

while (1); /* break here */

}

int

main (void)

{

int i;

alarm (300);

pthread_barrier_init (&barrier, NULL, NUM_THREADS);

for (i = 0; i < NUM_THREADS; i++)

{

pthread_t thread;

int res;

res = pthread_create (&thread, NULL, thread_function, NULL);

assert (res == 0);

}

while (1)

sleep (1);

return 0;

}



Sample output without patch changes in aix-thread.c at line 921 and 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;



Summary of the gdb.base testsuites.



Without Patch
------------------------

# of expected passes

8096

# of unexpected failures

2160

# of unexpected successes

1

# of expected failures

4

# of known failures

5

# of unresolved testcases

113

# of untested testcases

83

# of unsupported tests

40

# of paths in test names

2

# of duplicate test names

13

With Patch
------------------------


# of expected passes

13822

# of unexpected failures

                    7399

# of unexpected successes

1

# of expected failures

11

# of known failures

6

# of unresolved testcases

78

# of untested testcases

88

# of unsupported tests

63

# of paths in test names

1

# of duplicate test names

2


(See attached file: 0001-Use-current_inferior-pid-for-AIX)


Thanks and regards,

Aditya.




________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Tuesday, April 5, 2022 6:17 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi Aditya,

I don't think that using current_inferior throughout is a good solution
to your problems.  It will be case by case, unfortunately there's no
easy way out of this but to dig in GDB and understand its internals a
bit.

> From eb10e0ebc422d01f5ce96786f0bcf78a4f57d7ef Mon Sep 17 00:00:00 2001
> From: Aditya Vidyadhar Kamath
>  <adityakamath@li-ee942a4f-4ab2-47e9-8494-fb53eafbb9e1.ibm.com>
> Date: Wed, 30 Mar 2022 11:19:14 +0530
> Subject: [PATCH] Use current_inferior ()->pid for AIX.
>
> ---
>  gdb/aix-thread.c     | 15 ++++++++-------
>  gdb/rs6000-aix-nat.c |  8 ++++----
>  2 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
> index 85be4c15f1c..9331de3beb2 100644
> --- a/gdb/aix-thread.c
> +++ b/gdb/aix-thread.c
> @@ -708,7 +708,7 @@ get_signaled_thread (void)
>
>    while (1)
>      {
> -      if (getthrds (inferior_ptid.pid (), &thrinf,
> +      if (getthrds (current_inferior ()->pid, &thrinf,
>                    sizeof (thrinf), &ktid, 1) != 1)

This function doesn't seem to depend on the current inferior/thread, so
it could easily be changed to receive the pid as a parameter.

>        break;
>
> @@ -791,7 +791,7 @@ sync_threadlists (void)
>
>    /* Apply differences between the two arrays to GDB's thread list.  */
>
> -  infpid = inferior_ptid.pid ();
> +  infpid = current_inferior ()->pid;
>    for (pi = gi = 0; pi < pcount || gi < gcount;)
>      {
>        if (pi == pcount)
> @@ -883,11 +883,11 @@ pd_update (int set_infpid)
>    struct thread_info *thread = NULL;
>
>    if (!pd_active)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);
>
>    status = pthdb_session_update (pd_session);
>    if (status != PTHDB_SUCCESS)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);

Here, the pd_update function seems to want to return the event ptid
unmodified.  So, perhaps that ptid could be passed by the caller and
returned here.  Or, pd_update could be changed to return an
optional<ptid_t> and the caller deals with returning the right ptid.

>
>    sync_threadlists ();
>
> @@ -897,7 +897,7 @@ pd_update (int set_infpid)
>    if (tid != 0)
>      thread = iterate_over_threads (iter_tid, &tid);
>    if (!thread)
> -    ptid = inferior_ptid;
> +    ptid = ptid_t (current_inferior ()->pid);
>    else
>      {
>        ptid = thread->ptid;
> @@ -921,7 +921,7 @@ pd_activate (int set_infpid)
>                               &pd_session);
>    if (status != PTHDB_SUCCESS)
>      {
> -      return inferior_ptid;
> +      return ptid_t (current_inferior ()->pid);

This is the same idea as in pd_update.

>      }
>    pd_active = 1;
>    return pd_update (set_infpid);
> @@ -932,11 +932,12 @@ pd_activate (int set_infpid)
>  static void
>  pd_deactivate (void)
>  {
> +  ptid_t ptdrtn = ptid_t (current_inferior ()->pid)
>    if (!pd_active)
>      return;
>    pthdb_session_destroy (pd_session);
>
> -  pid_to_prc (&inferior_ptid);
> +  pid_to_prc (&ptdrtn);

Since pid_to_prc only writes to ptdrtn, it essentially a no-op.  I would
try just removing that call.  It was used to modify inferior_ptid after
the thread layer was disabled, which does not seem useful to me.

> diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
> index 8563aea313a..0b8e4d2c687 100644
> --- a/gdb/rs6000-aix-nat.c
> +++ b/gdb/rs6000-aix-nat.c
> @@ -397,7 +397,7 @@ rs6000_nat_target::xfer_partial (enum target_object object,
>                                 ULONGEST offset, ULONGEST len,
>                                 ULONGEST *xfered_len)
>  {
> -  pid_t pid = inferior_ptid.pid ();
> +  pid_t pid = current_inferior ()->pid;
>    int arch64 = ARCH64 ();
>
>    switch (object)

Here, inferior_ptid should be valid, this change should not be
necessary.

> @@ -525,11 +525,11 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>
>          /* Claim it exited with unknown signal.  */
>          ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
> -       return inferior_ptid;
> +       return ptid_t (current_inferior ()->pid);
>        }
>
>        /* Ignore terminated detached child processes.  */
> -      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
> +      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
>        pid = -1;
>      }
>    while (pid == -1);

The target_ops::wait method implemenattions should ne rely on the
current inferior either.  I don't think that this target supports
debugging multiple processes at the same time, but imagine that it does,
eventually.  When rs6000_nat_target::wait gets called, the current
inferior is one of the inferiors managed by that target, at random.  So
what the wait method needs to do is fetch an event from the OS, and
returning, regardless of which inferior it applies to (except if a ptid
argument is given).  So, you should never need to use either
inferior_ptid nor current_inferior in wait.

> @@ -658,7 +658,7 @@ rs6000_nat_target::xfer_shared_libraries
>    if (writebuf)
>      return TARGET_XFER_E_IO;
>
> -  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
> +  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t(current_inferior ()->pid));
>    result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
>                                      readbuf, offset, len, 1);

This is used by xfer_partial, where inferior_ptid should be valid, so
this change shouldn't be necessary.

Simon

[-- Attachment #2: 0001-Use-current_inferior-pid-for-AIX.patch --]
[-- Type: application/octet-stream, Size: 1476 bytes --]

From 8ffe8f82e27cff8643644a5f3ac8c9e7f3e3a460 Mon Sep 17 00:00:00 2001
From: "aditya@ibm" <aditya.vidyadhar.kamath@ibm.com>
Date: Tue, 12 Apr 2022 07:08:46 -0500
Subject: [PATCH] Use current_inferior ()->pid for AIX

---
 gdb/aix-thread.c     | 4 ++--
 gdb/rs6000-aix-nat.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index 6a4b469788a..47d612c960b 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -883,7 +883,7 @@ pd_update (int set_infpid)
   struct thread_info *thread = NULL;
 
   if (!pd_active)
-    return inferior_ptid;
+    return ptid_t (current_inferior ()->pid);
 
   status = pthdb_session_update (pd_session);
   if (status != PTHDB_SUCCESS)
@@ -921,7 +921,7 @@ pd_activate (int set_infpid)
 			       &pd_session);
   if (status != PTHDB_SUCCESS)
     {
-      return inferior_ptid;
+      return ptid_t (current_inferior ()->pid);
     }
   pd_active = 1;
   return pd_update (set_infpid);
diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
index 5cf1214c65e..d4d181b155e 100644
--- a/gdb/rs6000-aix-nat.c
+++ b/gdb/rs6000-aix-nat.c
@@ -529,7 +529,7 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
 	}
 
       /* Ignore terminated detached child processes.  */
-      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
+      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
 	pid = -1;
     }
   while (pid == -1);
-- 
2.31.1

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

Any update on this?

Kindly let me know.

Thanks and regards,
Aditya.
________________________________
From: Gdb-patches <gdb-patches-bounces+aditya.vidyadhar.kamath=ibm.com@sourceware.org> on behalf of Aditya Vidyadhar Kamath via Gdb-patches <gdb-patches@sourceware.org>
Sent: Tuesday, April 12, 2022 7:02 PM
To: Simon Marchi <simon.marchi@polymtl.ca>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi,

A case by case analysis as suggested by you the last time has been done.

While the child process [the program to be debugged] is running inferior_ptid.pid() will not contain the child process ID. One has to use pid_t(current_inferior ()->pid) inorder to get the child process in AIX. GDB may allow you to execute many programmes at the same time. Numerous threads of execution can be initiated from multiple executables in each of multiple processes.

GDB uses an inferior object to represent the status of each programme run. An inferior usually correlates to a process, although it is more broad and may be used to targets without processes as well. Inferiors can be produced before a process runs and kept after it has completed. Inferiors have their own unique IDs, which are not the same as process ids. Each inferior may have several threads going through it. As a result, inferior ptid.pid may not need to contain the current inferior thread id. To obtain the inferior process ID, we must utilise current inferior()->pid in particular areas.

When the child process's pd_active variable is not set i.e. the process is not active one has to use the pid_t(current_inferior ()->pid) instead of inferior_ptid.pid() in AIX.

This can be demonstrated by the following code:


#include <stdio.h>

#include <stdlib.h>

int main()

{

   int i = 1;

   return 0;

}

Sample output without patch changes only in aix-thread.c at line 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Sample output with patch changes in aix-thread.c and without patch changes in rs6000-aix-nat.c:


Child process unexpectedly missing: There are no child processes..

Program terminated with signal ?, Unknown signal.

The program no longer exists.

Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;


-------------------------------------------

When there are multiple threads running in a debugging process, inferior_ptid will not have the exact current inferior thread. Instead we need to use ptid_t (current_inferior ()->pid) to get it in AIX.


This can be shown by the following program:


#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <pthread.h>

#include <assert.h>

pthread_barrier_t barrier;

#define NUM_THREADS 2

void *

thread_function (void *arg)

{

pthread_barrier_wait (&barrier);

while (1); /* break here */

}

int

main (void)

{

int i;

alarm (300);

pthread_barrier_init (&barrier, NULL, NUM_THREADS);

for (i = 0; i < NUM_THREADS; i++)

{

pthread_t thread;

int res;

res = pthread_create (&thread, NULL, thread_function, NULL);

assert (res == 0);

}

while (1)

sleep (1);

return 0;

}



Sample output without patch changes in aix-thread.c at line 921 and 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;



Summary of the gdb.base testsuites.



Without Patch
------------------------

# of expected passes

8096

# of unexpected failures

2160

# of unexpected successes

1

# of expected failures

4

# of known failures

5

# of unresolved testcases

113

# of untested testcases

83

# of unsupported tests

40

# of paths in test names

2

# of duplicate test names

13

With Patch
------------------------


# of expected passes

13822

# of unexpected failures

                    7399

# of unexpected successes

1

# of expected failures

11

# of known failures

6

# of unresolved testcases

78

# of untested testcases

88

# of unsupported tests

63

# of paths in test names

1

# of duplicate test names

2


(See attached file: 0001-Use-current_inferior-pid-for-AIX)


Thanks and regards,

Aditya.




________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Tuesday, April 5, 2022 6:17 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi Aditya,

I don't think that using current_inferior throughout is a good solution
to your problems.  It will be case by case, unfortunately there's no
easy way out of this but to dig in GDB and understand its internals a
bit.

> From eb10e0ebc422d01f5ce96786f0bcf78a4f57d7ef Mon Sep 17 00:00:00 2001
> From: Aditya Vidyadhar Kamath
>  <adityakamath@li-ee942a4f-4ab2-47e9-8494-fb53eafbb9e1.ibm.com>
> Date: Wed, 30 Mar 2022 11:19:14 +0530
> Subject: [PATCH] Use current_inferior ()->pid for AIX.
>
> ---
>  gdb/aix-thread.c     | 15 ++++++++-------
>  gdb/rs6000-aix-nat.c |  8 ++++----
>  2 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
> index 85be4c15f1c..9331de3beb2 100644
> --- a/gdb/aix-thread.c
> +++ b/gdb/aix-thread.c
> @@ -708,7 +708,7 @@ get_signaled_thread (void)
>
>    while (1)
>      {
> -      if (getthrds (inferior_ptid.pid (), &thrinf,
> +      if (getthrds (current_inferior ()->pid, &thrinf,
>                    sizeof (thrinf), &ktid, 1) != 1)

This function doesn't seem to depend on the current inferior/thread, so
it could easily be changed to receive the pid as a parameter.

>        break;
>
> @@ -791,7 +791,7 @@ sync_threadlists (void)
>
>    /* Apply differences between the two arrays to GDB's thread list.  */
>
> -  infpid = inferior_ptid.pid ();
> +  infpid = current_inferior ()->pid;
>    for (pi = gi = 0; pi < pcount || gi < gcount;)
>      {
>        if (pi == pcount)
> @@ -883,11 +883,11 @@ pd_update (int set_infpid)
>    struct thread_info *thread = NULL;
>
>    if (!pd_active)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);
>
>    status = pthdb_session_update (pd_session);
>    if (status != PTHDB_SUCCESS)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);

Here, the pd_update function seems to want to return the event ptid
unmodified.  So, perhaps that ptid could be passed by the caller and
returned here.  Or, pd_update could be changed to return an
optional<ptid_t> and the caller deals with returning the right ptid.

>
>    sync_threadlists ();
>
> @@ -897,7 +897,7 @@ pd_update (int set_infpid)
>    if (tid != 0)
>      thread = iterate_over_threads (iter_tid, &tid);
>    if (!thread)
> -    ptid = inferior_ptid;
> +    ptid = ptid_t (current_inferior ()->pid);
>    else
>      {
>        ptid = thread->ptid;
> @@ -921,7 +921,7 @@ pd_activate (int set_infpid)
>                               &pd_session);
>    if (status != PTHDB_SUCCESS)
>      {
> -      return inferior_ptid;
> +      return ptid_t (current_inferior ()->pid);

This is the same idea as in pd_update.

>      }
>    pd_active = 1;
>    return pd_update (set_infpid);
> @@ -932,11 +932,12 @@ pd_activate (int set_infpid)
>  static void
>  pd_deactivate (void)
>  {
> +  ptid_t ptdrtn = ptid_t (current_inferior ()->pid)
>    if (!pd_active)
>      return;
>    pthdb_session_destroy (pd_session);
>
> -  pid_to_prc (&inferior_ptid);
> +  pid_to_prc (&ptdrtn);

Since pid_to_prc only writes to ptdrtn, it essentially a no-op.  I would
try just removing that call.  It was used to modify inferior_ptid after
the thread layer was disabled, which does not seem useful to me.

> diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
> index 8563aea313a..0b8e4d2c687 100644
> --- a/gdb/rs6000-aix-nat.c
> +++ b/gdb/rs6000-aix-nat.c
> @@ -397,7 +397,7 @@ rs6000_nat_target::xfer_partial (enum target_object object,
>                                 ULONGEST offset, ULONGEST len,
>                                 ULONGEST *xfered_len)
>  {
> -  pid_t pid = inferior_ptid.pid ();
> +  pid_t pid = current_inferior ()->pid;
>    int arch64 = ARCH64 ();
>
>    switch (object)

Here, inferior_ptid should be valid, this change should not be
necessary.

> @@ -525,11 +525,11 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>
>          /* Claim it exited with unknown signal.  */
>          ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
> -       return inferior_ptid;
> +       return ptid_t (current_inferior ()->pid);
>        }
>
>        /* Ignore terminated detached child processes.  */
> -      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
> +      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
>        pid = -1;
>      }
>    while (pid == -1);

The target_ops::wait method implemenattions should ne rely on the
current inferior either.  I don't think that this target supports
debugging multiple processes at the same time, but imagine that it does,
eventually.  When rs6000_nat_target::wait gets called, the current
inferior is one of the inferiors managed by that target, at random.  So
what the wait method needs to do is fetch an event from the OS, and
returning, regardless of which inferior it applies to (except if a ptid
argument is given).  So, you should never need to use either
inferior_ptid nor current_inferior in wait.

> @@ -658,7 +658,7 @@ rs6000_nat_target::xfer_shared_libraries
>    if (writebuf)
>      return TARGET_XFER_E_IO;
>
> -  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
> +  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t(current_inferior ()->pid));
>    result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
>                                      readbuf, offset, len, 1);

This is used by xfer_partial, where inferior_ptid should be valid, so
this change shouldn't be necessary.

Simon

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

Hi Simon,

Any update on this?

Kindly let me know.

Thanks and regards,
Aditya.
________________________________
From: Gdb-patches <gdb-patches-bounces+aditya.vidyadhar.kamath=ibm.com@sourceware.org> on behalf of Aditya Vidyadhar Kamath via Gdb-patches <gdb-patches@sourceware.org>
Sent: Tuesday, April 12, 2022 7:02 PM
To: Simon Marchi <simon.marchi@polymtl.ca>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi,

A case by case analysis as suggested by you the last time has been done.

While the child process [the program to be debugged] is running inferior_ptid.pid() will not contain the child process ID. One has to use pid_t(current_inferior ()->pid) inorder to get the child process in AIX. GDB may allow you to execute many programmes at the same time. Numerous threads of execution can be initiated from multiple executables in each of multiple processes.

GDB uses an inferior object to represent the status of each programme run. An inferior usually correlates to a process, although it is more broad and may be used to targets without processes as well. Inferiors can be produced before a process runs and kept after it has completed. Inferiors have their own unique IDs, which are not the same as process ids. Each inferior may have several threads going through it. As a result, inferior ptid.pid may not need to contain the current inferior thread id. To obtain the inferior process ID, we must utilise current inferior()->pid in particular areas.

When the child process's pd_active variable is not set i.e. the process is not active one has to use the pid_t(current_inferior ()->pid) instead of inferior_ptid.pid() in AIX.

This can be demonstrated by the following code:


#include <stdio.h>

#include <stdlib.h>

int main()

{

   int i = 1;

   return 0;

}

Sample output without patch changes only in aix-thread.c at line 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Sample output with patch changes in aix-thread.c and without patch changes in rs6000-aix-nat.c:


Child process unexpectedly missing: There are no child processes..

Program terminated with signal ?, Unknown signal.

The program no longer exists.

Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;


-------------------------------------------

When there are multiple threads running in a debugging process, inferior_ptid will not have the exact current inferior thread. Instead we need to use ptid_t (current_inferior ()->pid) to get it in AIX.


This can be shown by the following program:


#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <pthread.h>

#include <assert.h>

pthread_barrier_t barrier;

#define NUM_THREADS 2

void *

thread_function (void *arg)

{

pthread_barrier_wait (&barrier);

while (1); /* break here */

}

int

main (void)

{

int i;

alarm (300);

pthread_barrier_init (&barrier, NULL, NUM_THREADS);

for (i = 0; i < NUM_THREADS; i++)

{

pthread_t thread;

int res;

res = pthread_create (&thread, NULL, thread_function, NULL);

assert (res == 0);

}

while (1)

sleep (1);

return 0;

}



Sample output without patch changes in aix-thread.c at line 921 and 883 and not in rs6000-aix-nat.c:


inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

----- Backtrace -----

0x100e87543 ???

0x100e8770b ???

0x10003724b ???

0x100037697 ???

0x1000363f3 ???

0x1000593a3 ???

0x1000594ff ???

0x10053aa9b ???

0x1002f6e7b ???

0x1002f2ec3 ???

0x100b26d43 ???

0x100302a03 ???

0x10077e413 ???

0x10077b1a7 ???

0x100001dff ???

0x100002007 ???

0x10000421b ???

0x1000042ef ???

0x100000a9f ???

0x100000583 ???

---------------------

inferior.c:303: internal-error: find_inferior_pid: Assertion `pid != 0' failed.


Output with patch:

(gdb) b main

Breakpoint 1 at 0x1000070c: file test.cc, line 3.

(gdb) r

Starting program: /home/gdb_tests/test

Breakpoint 1, main () at test.cc:3

3 int i = 1;



Summary of the gdb.base testsuites.



Without Patch
------------------------

# of expected passes

8096

# of unexpected failures

2160

# of unexpected successes

1

# of expected failures

4

# of known failures

5

# of unresolved testcases

113

# of untested testcases

83

# of unsupported tests

40

# of paths in test names

2

# of duplicate test names

13

With Patch
------------------------


# of expected passes

13822

# of unexpected failures

                    7399

# of unexpected successes

1

# of expected failures

11

# of known failures

6

# of unresolved testcases

78

# of untested testcases

88

# of unsupported tests

63

# of paths in test names

1

# of duplicate test names

2


(See attached file: 0001-Use-current_inferior-pid-for-AIX)


Thanks and regards,

Aditya.




________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Tuesday, April 5, 2022 6:17 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>; Joel Brobecker via Gdb-patches <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi Aditya,

I don't think that using current_inferior throughout is a good solution
to your problems.  It will be case by case, unfortunately there's no
easy way out of this but to dig in GDB and understand its internals a
bit.

> From eb10e0ebc422d01f5ce96786f0bcf78a4f57d7ef Mon Sep 17 00:00:00 2001
> From: Aditya Vidyadhar Kamath
>  <adityakamath@li-ee942a4f-4ab2-47e9-8494-fb53eafbb9e1.ibm.com>
> Date: Wed, 30 Mar 2022 11:19:14 +0530
> Subject: [PATCH] Use current_inferior ()->pid for AIX.
>
> ---
>  gdb/aix-thread.c     | 15 ++++++++-------
>  gdb/rs6000-aix-nat.c |  8 ++++----
>  2 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
> index 85be4c15f1c..9331de3beb2 100644
> --- a/gdb/aix-thread.c
> +++ b/gdb/aix-thread.c
> @@ -708,7 +708,7 @@ get_signaled_thread (void)
>
>    while (1)
>      {
> -      if (getthrds (inferior_ptid.pid (), &thrinf,
> +      if (getthrds (current_inferior ()->pid, &thrinf,
>                    sizeof (thrinf), &ktid, 1) != 1)

This function doesn't seem to depend on the current inferior/thread, so
it could easily be changed to receive the pid as a parameter.

>        break;
>
> @@ -791,7 +791,7 @@ sync_threadlists (void)
>
>    /* Apply differences between the two arrays to GDB's thread list.  */
>
> -  infpid = inferior_ptid.pid ();
> +  infpid = current_inferior ()->pid;
>    for (pi = gi = 0; pi < pcount || gi < gcount;)
>      {
>        if (pi == pcount)
> @@ -883,11 +883,11 @@ pd_update (int set_infpid)
>    struct thread_info *thread = NULL;
>
>    if (!pd_active)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);
>
>    status = pthdb_session_update (pd_session);
>    if (status != PTHDB_SUCCESS)
> -    return inferior_ptid;
> +    return ptid_t (current_inferior ()->pid);

Here, the pd_update function seems to want to return the event ptid
unmodified.  So, perhaps that ptid could be passed by the caller and
returned here.  Or, pd_update could be changed to return an
optional<ptid_t> and the caller deals with returning the right ptid.

>
>    sync_threadlists ();
>
> @@ -897,7 +897,7 @@ pd_update (int set_infpid)
>    if (tid != 0)
>      thread = iterate_over_threads (iter_tid, &tid);
>    if (!thread)
> -    ptid = inferior_ptid;
> +    ptid = ptid_t (current_inferior ()->pid);
>    else
>      {
>        ptid = thread->ptid;
> @@ -921,7 +921,7 @@ pd_activate (int set_infpid)
>                               &pd_session);
>    if (status != PTHDB_SUCCESS)
>      {
> -      return inferior_ptid;
> +      return ptid_t (current_inferior ()->pid);

This is the same idea as in pd_update.

>      }
>    pd_active = 1;
>    return pd_update (set_infpid);
> @@ -932,11 +932,12 @@ pd_activate (int set_infpid)
>  static void
>  pd_deactivate (void)
>  {
> +  ptid_t ptdrtn = ptid_t (current_inferior ()->pid)
>    if (!pd_active)
>      return;
>    pthdb_session_destroy (pd_session);
>
> -  pid_to_prc (&inferior_ptid);
> +  pid_to_prc (&ptdrtn);

Since pid_to_prc only writes to ptdrtn, it essentially a no-op.  I would
try just removing that call.  It was used to modify inferior_ptid after
the thread layer was disabled, which does not seem useful to me.

> diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
> index 8563aea313a..0b8e4d2c687 100644
> --- a/gdb/rs6000-aix-nat.c
> +++ b/gdb/rs6000-aix-nat.c
> @@ -397,7 +397,7 @@ rs6000_nat_target::xfer_partial (enum target_object object,
>                                 ULONGEST offset, ULONGEST len,
>                                 ULONGEST *xfered_len)
>  {
> -  pid_t pid = inferior_ptid.pid ();
> +  pid_t pid = current_inferior ()->pid;
>    int arch64 = ARCH64 ();
>
>    switch (object)

Here, inferior_ptid should be valid, this change should not be
necessary.

> @@ -525,11 +525,11 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>
>          /* Claim it exited with unknown signal.  */
>          ourstatus->set_signalled (GDB_SIGNAL_UNKNOWN);
> -       return inferior_ptid;
> +       return ptid_t (current_inferior ()->pid);
>        }
>
>        /* Ignore terminated detached child processes.  */
> -      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
> +      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))
>        pid = -1;
>      }
>    while (pid == -1);

The target_ops::wait method implemenattions should ne rely on the
current inferior either.  I don't think that this target supports
debugging multiple processes at the same time, but imagine that it does,
eventually.  When rs6000_nat_target::wait gets called, the current
inferior is one of the inferiors managed by that target, at random.  So
what the wait method needs to do is fetch an event from the OS, and
returning, regardless of which inferior it applies to (except if a ptid
argument is given).  So, you should never need to use either
inferior_ptid nor current_inferior in wait.

> @@ -658,7 +658,7 @@ rs6000_nat_target::xfer_shared_libraries
>    if (writebuf)
>      return TARGET_XFER_E_IO;
>
> -  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
> +  gdb::byte_vector ldi_buf = rs6000_ptrace_ldinfo (ptid_t(current_inferior ()->pid));
>    result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf.data (),
>                                      readbuf, offset, len, 1);

This is used by xfer_partial, where inferior_ptid should be valid, so
this change shouldn't be necessary.

Simon

Re: [PATCH] Use current_inferior ()->pid for AIX

[Simon Marchi]

> diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
> index 5cf1214c65e..d4d181b155e 100644
> --- a/gdb/rs6000-aix-nat.c
> +++ b/gdb/rs6000-aix-nat.c
> @@ -529,7 +529,7 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
>  	}
>
>        /* Ignore terminated detached child processes.  */
> -      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
> +      if (!WIFSTOPPED (status) && pid != pid_t(current_inferior ()->pid))

As stated in my previous message, you should not assume which is the
current inferior, when entering the wait method.  The current code was
written a while ago, probably before GDB gained support for
multi-inferior.  So if we are to change this code, we should bring it up
to current standards, as much as possible.

Imagine that your target is currently debugging two inferiors executing
simultaneously (I don't know if the AIX target supports that, but let's
pretend that it does).  The event you get from waitpid could be for
either inferior.  So you can't simply ignore an event if it is for the
non-current inferior.

When you have a multi-threaded (pthread) inferior on AIX and call
waitpid on it, what does it return when some thread get a signal?  Does
it return the pid of the process, or a specific tid?  My reading of the
code in aix-thread.c and of the snippet above makes me think that the
kernel returns the process' pid.  And then get_signaled_thread in
aix-thread.c takes care of finding the specific thread that got a
signal, somehow.

So my intuition is that here it would make sense to call
find_inferior_pid with the value returned by waitpid, to see if this is
for an inferior we know or for a "terminated detached child process", as
the comment above says.  If we have no inferior with that pid, we can
probably ignore the event.  If we have an inferior with that pid, then
we return its pid and status.

Note that inferior_ptid variable at this point will still be null_ptid
(and that's ok).  Back in aix_thread_target::wait (if using the
aix-thread target), the simplest thing to do is probably to call
find_inferior_pid with the pid returned by `beneath ()->wait` and make
it the current inferior with switch_to_inferior_no_thread.  Then, the
rest of the code (pd_update and pd_activate) can correctly assume that
they have the right current inferior, so can use
`current_inferior()->pid`.

I don't know if that actually makes sense.  I would actually try it on
an AIX machine on the GCC compile farm, but I can't get GDB to build on
it, and I don't really have time to look into it:

  CXX      thread-pool.o
In file included from ../../src/binutils-gdb/gdbsupport/thread-pool.cc:21:0:
../../src/binutils-gdb/gdbsupport/../gdbsupport/thread-pool.h: In member function 'std::future<void> gdb::thread_pool::post_task(std::function<void()>&&)':
../../src/binutils-gdb/gdbsupport/../gdbsupport/thread-pool.h:68:3: error: return type 'class std::future<void>' is incomplete

Simon

Re: [PATCH] Use current_inferior ()->pid for AIX

[Simon Marchi]

Hi,

Re-adding gdb-patches, since it's information useful to everybody.

On 2022-05-29 23:41, Aditya Vidyadhar Kamath wrote:
> Hi Simon,
> 
> Thank you so much for the feedback. Yes it makes sense. As I was trying to fix this we need one more information that will help us. 
> 
> Once an inferior finishes its execution where is the inferior_ptid's pid variable set to 0. Or who is the one [file name or function name] that updates inferior_ptid class variable pid to 0. 

This is done in the mourn_inferior target method.  Many targets call the
generic_mourn_inferior function, which calls switch_to_no_thread, which
sets current_thread_ to nullptr and inferior_ptid to null_ptid.

Simon

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

[-- Attachment #1: Type: text/plain, Size: 3041 bytes --]

Hi all,

While testing programs in AIX I noticed that GDB crashes when an
inferior exits, with this error:

  inferior.c:293: internal- error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.

When a process exits inferior_ptid.pid is set to 0. Unfortunately, the rs6000-aix-nat target is still relying on the value of
inferior_ptid in the case where an inferior exits - we return the
value of inferior_ptid as the pid of the process that exited.

The waitpid() system call suspends execution of the calling process until a child specified by pid argument has changed state. Once the inferior [assuming there is only one inferior] dies, waitpid() has no child to return.

Due to this an ERRCHLD error is returned thereby returning an inferior_ptid.pid with 0 leading to this assertion failure.

This patch is a fix to the same where we use the pid returned by the beneath wait using waitpid and adjust our inferior_ptid so that the rest of the code will take in the right values of both inferior_ptid and current_inferior.

The following are the test results after running gdb.base test suite with the patch.
# of expected passes 26244
# of unexpected failures 4230
# of unexpected successes 1
# of expected failures 17
# of known failures 26
# of unresolved testcases 110
# of untested testcases 79
# of unsupported tests 62
# of paths in test names 1
# of duplicate test names 4

The following are test results after running gdb.base test suite without the patch.
# of expected passes 12935
# of unexpected failures 1988
# of unexpected successes 1
# of expected failures 3
# of known failures 6
# of unresolved testcases 159
# of untested testcases 77
# of unsupported tests 39
# of paths in test names 2
# of duplicate test names 13

Please find attached the patch. [See 0001-Fix-gdb_assert-pid-0-assertion-failure-in-AIX.patch].

Have a nice day ahead,

Thanks and regards,
Aditya.


________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Monday, May 30, 2022 6:15 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi,

Re-adding gdb-patches, since it's information useful to everybody.

On 2022-05-29 23:41, Aditya Vidyadhar Kamath wrote:
> Hi Simon,
>
> Thank you so much for the feedback. Yes it makes sense. As I was trying to fix this we need one more information that will help us.
>
> Once an inferior finishes its execution where is the inferior_ptid's pid variable set to 0. Or who is the one [file name or function name] that updates inferior_ptid class variable pid to 0.

This is done in the mourn_inferior target method.  Many targets call the
generic_mourn_inferior function, which calls switch_to_no_thread, which
sets current_thread_ to nullptr and inferior_ptid to null_ptid.

Simon

[-- Attachment #2: 0001-Fix-gdb_assert-pid-0-assertion-failure-in-AIX.patch --]
[-- Type: application/octet-stream, Size: 1703 bytes --]

From f8259070349b075f65a4b9fe0a888543a6864f6e Mon Sep 17 00:00:00 2001
From: "aditya@ibm" <aditya.vidyadhar.kamath@ibm.com>
Date: Fri, 10 Jun 2022 08:50:46 -0500
Subject: [PATCH] Fix gdb_assert (pid != 0); assertion failure in AIX

---
 gdb/aix-thread.c     | 5 +++++
 gdb/rs6000-aix-nat.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index ecd8200b692..3037d73c5c4 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -1079,6 +1079,7 @@ ptid_t
 aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
 			 target_wait_flags options)
 {
+  struct inferior *inf;
   {
     scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
 
@@ -1091,6 +1092,10 @@ aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
   if (ptid.pid () == -1)
     return ptid_t (-1);
 
+  inf = find_inferior_pid(current_inferior ()->process_target (),ptid.pid());
+  if(inf != NULL){
+   inferior_ptid = ptid;
+  }
   /* Check whether libpthdebug might be ready to be initialized.  */
   if (!pd_active && status->kind () == TARGET_WAITKIND_STOPPED
       && status->sig () == GDB_SIGNAL_TRAP)
diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
index 8563aea313a..8a0c074be8f 100644
--- a/gdb/rs6000-aix-nat.c
+++ b/gdb/rs6000-aix-nat.c
@@ -529,7 +529,7 @@ rs6000_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
 	}
 
       /* Ignore terminated detached child processes.  */
-      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid ())
+      if (!WIFSTOPPED (status) && pid != inferior_ptid.pid () && inferior_ptid.pid () != 0)
 	pid = -1;
     }
   while (pid == -1);
-- 
2.31.1

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

Hi all,

Kindly give us a feedback for this update.

Thanks and regards,
Aditya
________________________________
From: Gdb-patches <gdb-patches-bounces+aditya.vidyadhar.kamath=ibm.com@sourceware.org> on behalf of Aditya Vidyadhar Kamath via Gdb-patches <gdb-patches@sourceware.org>
Sent: Friday, June 10, 2022 8:17 PM
To: Simon Marchi <simon.marchi@polymtl.ca>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi all,

While testing programs in AIX I noticed that GDB crashes when an
inferior exits, with this error:

  inferior.c:293: internal- error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.

When a process exits inferior_ptid.pid is set to 0. Unfortunately, the rs6000-aix-nat target is still relying on the value of
inferior_ptid in the case where an inferior exits - we return the
value of inferior_ptid as the pid of the process that exited.

The waitpid() system call suspends execution of the calling process until a child specified by pid argument has changed state. Once the inferior [assuming there is only one inferior] dies, waitpid() has no child to return.

Due to this an ERRCHLD error is returned thereby returning an inferior_ptid.pid with 0 leading to this assertion failure.

This patch is a fix to the same where we use the pid returned by the beneath wait using waitpid and adjust our inferior_ptid so that the rest of the code will take in the right values of both inferior_ptid and current_inferior.

The following are the test results after running gdb.base test suite with the patch.
# of expected passes 26244
# of unexpected failures 4230
# of unexpected successes 1
# of expected failures 17
# of known failures 26
# of unresolved testcases 110
# of untested testcases 79
# of unsupported tests 62
# of paths in test names 1
# of duplicate test names 4

The following are test results after running gdb.base test suite without the patch.
# of expected passes 12935
# of unexpected failures 1988
# of unexpected successes 1
# of expected failures 3
# of known failures 6
# of unresolved testcases 159
# of untested testcases 77
# of unsupported tests 39
# of paths in test names 2
# of duplicate test names 13

Please find attached the patch. [See 0001-Fix-gdb_assert-pid-0-assertion-failure-in-AIX.patch].

Have a nice day ahead,

Thanks and regards,
Aditya.


________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Monday, May 30, 2022 6:15 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi,

Re-adding gdb-patches, since it's information useful to everybody.

On 2022-05-29 23:41, Aditya Vidyadhar Kamath wrote:
> Hi Simon,
>
> Thank you so much for the feedback. Yes it makes sense. As I was trying to fix this we need one more information that will help us.
>
> Once an inferior finishes its execution where is the inferior_ptid's pid variable set to 0. Or who is the one [file name or function name] that updates inferior_ptid class variable pid to 0.

This is done in the mourn_inferior target method.  Many targets call the
generic_mourn_inferior function, which calls switch_to_no_thread, which
sets current_thread_ to nullptr and inferior_ptid to null_ptid.

Simon

RE: [PATCH] Use current_inferior ()->pid for AIX

[Aditya Vidyadhar Kamath]

Hi all,

Kindly give us a feedback for this patch update.

Thanks and regards,
Aditya

________________________________
From: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>
Sent: Wednesday, June 15, 2022 9:33 AM
To: Simon Marchi <simon.marchi@polymtl.ca>; Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: Re: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi all,

Kindly give us a feedback for this update.

Thanks and regards,
Aditya
________________________________
From: Gdb-patches <gdb-patches-bounces+aditya.vidyadhar.kamath=ibm.com@sourceware.org> on behalf of Aditya Vidyadhar Kamath via Gdb-patches <gdb-patches@sourceware.org>
Sent: Friday, June 10, 2022 8:17 PM
To: Simon Marchi <simon.marchi@polymtl.ca>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: [EXTERNAL] RE: [PATCH] Use current_inferior ()->pid for AIX

Hi all,

While testing programs in AIX I noticed that GDB crashes when an
inferior exits, with this error:

  inferior.c:293: internal- error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed.

When a process exits inferior_ptid.pid is set to 0. Unfortunately, the rs6000-aix-nat target is still relying on the value of
inferior_ptid in the case where an inferior exits - we return the
value of inferior_ptid as the pid of the process that exited.

The waitpid() system call suspends execution of the calling process until a child specified by pid argument has changed state. Once the inferior [assuming there is only one inferior] dies, waitpid() has no child to return.

Due to this an ERRCHLD error is returned thereby returning an inferior_ptid.pid with 0 leading to this assertion failure.

This patch is a fix to the same where we use the pid returned by the beneath wait using waitpid and adjust our inferior_ptid so that the rest of the code will take in the right values of both inferior_ptid and current_inferior.

The following are the test results after running gdb.base test suite with the patch.
# of expected passes 26244
# of unexpected failures 4230
# of unexpected successes 1
# of expected failures 17
# of known failures 26
# of unresolved testcases 110
# of untested testcases 79
# of unsupported tests 62
# of paths in test names 1
# of duplicate test names 4

The following are test results after running gdb.base test suite without the patch.
# of expected passes 12935
# of unexpected failures 1988
# of unexpected successes 1
# of expected failures 3
# of known failures 6
# of unresolved testcases 159
# of untested testcases 77
# of unsupported tests 39
# of paths in test names 2
# of duplicate test names 13

Please find attached the patch. [See 0001-Fix-gdb_assert-pid-0-assertion-failure-in-AIX.patch].

Have a nice day ahead,

Thanks and regards,
Aditya.


________________________________
From: Simon Marchi <simon.marchi@polymtl.ca>
Sent: Monday, May 30, 2022 6:15 PM
To: Aditya Vidyadhar Kamath <ADITYA.VIDYADHAR.KAMATH@ibm.com>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
Subject: [EXTERNAL] Re: [PATCH] Use current_inferior ()->pid for AIX

Hi,

Re-adding gdb-patches, since it's information useful to everybody.

On 2022-05-29 23:41, Aditya Vidyadhar Kamath wrote:
> Hi Simon,
>
> Thank you so much for the feedback. Yes it makes sense. As I was trying to fix this we need one more information that will help us.
>
> Once an inferior finishes its execution where is the inferior_ptid's pid variable set to 0. Or who is the one [file name or function name] that updates inferior_ptid class variable pid to 0.

This is done in the mourn_inferior target method.  Many targets call the
generic_mourn_inferior function, which calls switch_to_no_thread, which
sets current_thread_ to nullptr and inferior_ptid to null_ptid.

Simon