Re: [PATCH] 0001-Fix-multi-thread-debug-bug-in-AIX.patch

[Aditya Kamath1 <Aditya.Kamath1@ibm.com>]

[-- Attachment #1.1: Type: text/plain, Size: 12099 bytes --]

Hi Ulrich, Tom and community,

Thank you for the feedback for the fix of this bug. Please find attached the patch. {See: 0001-Fix-multi-thread-debug-bug-in-AIX.patch}.

So, I have fixed the bug and it works alright. Please find the test program, output with patch and without patch pasted below this email.


>I'm not sure why the pd_active test is needed here
>at all - if ptid.tid () != 0, thread debugging *must*
>be active, otherwise you'd never have installed a ptid
>with the tid field set, right?

May be in the previous versions it was needed as they were adding main process as an extra thread. In this version of the aix-thread.c there is no place I have found where pd_active is disabled and we have a tid > 0. For us to have a tid we need pd_active enabled anyway which happens in pd_activate (). Otherwise, execution will not get into sync_threadlists () to set the tid.  So, I have removed it from there as you suggested.

>> static CORE_ADDR pd_brk_addr;

>I believe this needs to go into the aix_thread_variables struct;

This is done. Kindly check in the patch.

>This only was a callback because it was called via
>iterate_over_threads.  Now that you're using the
>all_threads C++ iterator, I think both of those

This is done. Kindly check in the patch.

>I think a simple but correct way to check whether the BFD filename
>already contains a member name is to check for the presence of an
>opening parenthesis e.g. via:
>   strrchr (bfd_get_filename (...), '(');

This is also done.

>I think the question here is simply whether, if you run the
>test suite both without and with your patch, are any of the
>FAILs fixed with the patch?   If not, it would be good to
>create a new test that fails without the patch and succeeds
>with it, and add that to the test suite.

So, this is something new to me. We will add it as a continuation in the same thread after this patch. I will need one information. Which test suite will we add it in? gdb.threads or gdb.base? Also, kindly suggest a simple test case that is written that I can see and learn. Any simple hello_world program will do. I want to understand how that exp file is written and how it compares to tell if a test case is pass or fail.

Kindly give me feedback for this patch, incase we can do anything better or is incorrect. If not, kindly push this patch so that AIX folks can have a better debugging experience.

Have a nice day ahead.

Thanks and regards,
Aditya.

-------------------------------------------
Code:-


#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)

{

  /* This ensures that the breakpoint is only hit after both threads

     are created, so the test can always switch to the non-event

     thread when the breakpoint triggers.  */


  pthread_barrier_wait (&barrier);

  pid_t child;


  child = fork ();

  if (child > 0)

    printf ("I am parent \n");

  else

  {

    child = fork ();

    if (child > 0)

      printf ("I am child \n");

    else

      printf ("I am grandchild \n");

  }

  while (1); /* break here */

}


int

main (void)

{

  int i;

  pthread_t thread[NUM_THREADS];


  alarm (300);


  pthread_barrier_init (&barrier, NULL, NUM_THREADS);


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

    {

      int res;


      res = pthread_create (&thread[i], NULL,

                            thread_function, NULL);

      assert (res == 0);

    }


  while (1)

  {

    sleep (15);

  }


  return 0;

}

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

Output with patch:-


Reading symbols from /home/aditya/gdb_tests/ultimate-multi-thread-fork...

(gdb) set detach-on-fork off

(gdb) r

Starting program: /home/aditya/gdb_tests/ultimate-multi-thread-fork

[New Thread 258]

[New Thread 515]

[New inferior 2 (process 18546974)]

[New inferior 3 (process 9634234)]

I am parent

I am parent

^C

Thread 1.1 received signal SIGINT, Interrupt.

[Switching to Thread 1]

0xd0595fb0 in _p_nsleep () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) info sharedlibrary

From        To          Syms Read   Shared Object Library

0xd05bc124  0xd05bf194  Yes (*)     /usr/lib/libpthreads.a(shr_comm.o)

0xd05bb240  0xd05bb9a1  Yes (*)     /usr/lib/libcrypt.a(shr.o)

0xd0576180  0xd05ba731  Yes (*)     /usr/lib/libpthread.a(shr_xpg5.o)

0xd0100e00  0xd0575123  Yes (*)     /usr/lib/libc.a(shr.o)

(*): Shared library is missing debugging information.

(gdb) info threads

  Id   Target Id                          Frame

* 1.1  Thread 1 (tid 27263453, running)   0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.2  Thread 258 (tid 29819289, running) thread_function (arg=0x0)

    at /home/aditya/gdb_tests/ultimate-multi-thread-fork.c:32

  1.3  Thread 515 (tid 25297199, running) thread_function (arg=0x0)


0x0)

    at /home/aditya/gdb_tests/ultimate-multi-thread-fork.c:32

  2.1  process 18546974                   0xd0594fc8 in _sigsetmask ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  3.1  process 9634234                    0xd0594fc8 in _sigsetmask ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) inferior 2

[Switching to inferior 2 [process 18546974] (/home/aditya/gdb_tests/ultimate-multi-thread-fork)]

[Switching to thread 2.1 (process 18546974)]

#0  0xd0594fc8 in _sigsetmask () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) info sharedlibrary

From        To          Syms Read   Shared Object Library

0xd05bc124  0xd05bf194  Yes (*)     /usr/lib/libpthreads.a(shr_comm.o)

0xd05bb240  0xd05bb9a1  Yes (*)     /usr/lib/libcrypt.a(shr.o)

0xd0576180  0xd05ba731  Yes (*)     /usr/lib/libpthread.a(shr_xpg5.o)

0xd0100e00  0xd0575123  Yes (*)     /usr/lib/libc.a(shr.o)

(*): Shared library is missing debugging information.

-----------------------------------------------------------------------
Output without patch:-
Reading symbols from /home/aditya/gdb_tests/ultimate-multi-thread-fork...

(gdb) set detach-on-fork off

(gdb) r

Starting program: /home/aditya/gdb_tests/ultimate-multi-thread-fork

[New Thread 1]

[New Thread 258]

[New Thread 515]

[New inferior 2 (process 11731200)]

I am parent

[New inferior 3 (process 16843200)]

I am parent

^C

Thread 1.1 received signal SIGINT, Interrupt.

0xd0595fb0 in _p_nsleep () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) inferior 2

[Switching to inferior 2 [process 11731200] (/home/aditya/gdb_tests/ultimate-multi-thread-fork)]

[Switching to thread 2.1 (process 11731200)]

#0  0xd0594fc8 in ?? ()

(gdb) info threads

  Id   Target Id         Frame

  1.1  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.2  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.3  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.4  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

* 2.1  process 11731200  0xd0594fc8 in ?? ()

  3.1  process 16843200  0xd0594fc8 in ?? ()

(gdb) info sharedlibrary

warning: "/usr/lib/libpthreads.a": member "shr_comm.o" missing.

warning: "/usr/lib/libcrypt.a": member "shr.o" missing.

warning: "/usr/lib/libpthread.a": member "shr_xpg5.o" missing.

warning: "/usr/lib/libc.a": member "shr.o" missing.

warning: Could not load shared library symbols for 4 libraries, e.g. /usr/lib/libpthreads.a(shr_comm.o).

Use the "info sharedlibrary" command to see the complete listing.

Do you need "set solib-search-path" or "set sysroot"?

From        To          Syms Read   Shared Object Library

                        No          /usr/lib/libpthreads.a(shr_comm.o)

                        No          /usr/lib/libcrypt.a(shr.o)

                        No          /usr/lib/libpthread.a(shr_xpg5.o)

                        No          /usr/lib/libc.a(shr.o)
(gdb)


________________________________
From: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Sent: 02 February 2023 23:13
To: simark@simark.ca <simark@simark.ca>; Aditya Kamath1 <Aditya.Kamath1@ibm.com>; gdb-patches@sourceware.org <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: Re: [PATCH] 0001-Fix-multi-thread-debug-bug-in-AIX.patch

Aditya Kamath1 <Aditya.Kamath1@ibm.com> wrote:

>>Is there an existing gdb test case that exercises this code?
>>If not then it seems like a new test is warranted.
>
>This I am not aware of at least when I tried finding.

I think the question here is simply whether, if you run the
test suite both without and with your patch, are any of the
FAILs fixed with the patch?   If not, it would be good to
create a new test that fails without the patch and succeeds
with it, and add that to the test suite.


I think we're getting pretty close now, but I do still have
some additional comments on the latest patch:

> /* Return whether to treat PID as a debuggable thread id.  */
>
>-#define PD_TID(ptid)  (pd_active && ptid.tid () != 0)
>+#define PD_TID(ptid, data)    (data->pd_active && ptid.tid () != 0)

I'm not sure why the pd_active test is needed here
at all - if ptid.tid () != 0, thread debugging *must*
be active, otherwise you'd never have installed a ptid
with the tid field set, right?

If that check can indeed be omitted, that would simplify
the patch a bit since you wouldn't need to provide the
"data" struct in quite as many places.

>/* Address of the function that libpthread will call when libpthdebug
>   is ready to be initialized.  */
>
> static CORE_ADDR pd_brk_addr;

I believe this needs to go into the aix_thread_variables struct;
the address might be different if the pthread library is loaded
at different addresses into different inferiors.

> /* Whether the current architecture is 64-bit.
>    Only valid when pd_able is true.  */
>
>static int arch64;

Likewise - some inferiors may be 64-bit and others 32-bit.

In general, *any* static variable in this file is suspect.


>+/* Callback for counting GDB threads for process pid.  */
>
> static int
>-giter_count (struct thread_info *thread, void *countp)
>+giter_count (pid_t pid)

This only was a callback because it was called via
iterate_over_threads.  Now that you're using the
all_threads C++ iterator, I think both of those
routines should just be inlined into its caller.


>@@ -565,6 +565,7 @@ solib_aix_bfd_open (const char *pathname)
>   const char *sep;
>   int filename_len;
>   int found_file;
>+  std::string string_path = pathname;
>
>   if (pathname[path_len - 1] != ')')
>     return solib_bfd_open (pathname);
>@@ -618,6 +619,15 @@ solib_aix_bfd_open (const char *pathname)
>       if (member_name == bfd_get_filename (object_bfd.get ()))
>        break;
>
>+      std::string s = bfd_get_filename (object_bfd.get ());
>+
>+      /* For every inferior after first int bfd system we
>+       will have the pathname instead of the member name
>+       registered. Hence the below condition exists.  */
>+
>+      if (string_path.compare (s) == 0)
>+      return object_bfd;

That's still not quite right, as the pathname component
might have been changed here:
  /* Calling solib_find makes certain that sysroot path is set properly
     if program has a dependency on .a archive and sysroot is set via
     set sysroot command.  */
  gdb::unique_xmalloc_ptr<char> found_pathname
    = solib_find (filename.c_str (), &found_file);

I think a simple but correct way to check whether the BFD filename
already contains a member name is to check for the presence of an
opening parenthesis e.g. via:
    strrchr (bfd_get_filename (...), '(');


Bye,
Ulrich


[-- Attachment #2: 0001-Fix-multi-thread-debug-bug-in-AIX.patch --]
[-- Type: application/octet-stream, Size: 26579 bytes --]

From 96613507fbf962eb90940c9763a60d2b50f6a46d Mon Sep 17 00:00:00 2001
From: Aditya Vidyadhar Kamath <Aditya.Kamath1@ibm.com>
Date: Fri, 3 Feb 2023 04:24:24 -0600
Subject: [PATCH] Fix Multi thread debug bug fix in AIX

 In the recent commit 98ed24fb35d89eb20179edf6c12f599c7a9e228e made by Mr. Tom there is a change in aix-thread.c file that changes

 static_cast <aix_thread_info *> in gdb to gdb::checked_static_cast <aix_thread_info *>

 AIX folks using the latest version will not be able to debug multi thread programs as a result of it

The error in AIX is as follows:-

internal-error checked_static_cast Assertion result != nullptr failed.

The reason being AIX shared library were not being loaded for a new inferior and top target was not set properly.

This patch is a fix for the same.
---
 gdb/aix-thread.c | 333 +++++++++++++++++++++++++++++------------------
 gdb/solib-aix.c  |  10 ++
 2 files changed, 219 insertions(+), 124 deletions(-)

diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index e556c153576..23e1aa6e90c 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -68,10 +68,6 @@ static bool debug_aix_thread;
 #define pthdb_tid_t	tid_t
 #endif
 
-/* Return whether to treat PID as a debuggable thread id.  */
-
-#define PD_TID(ptid)	(pd_active && ptid.tid () != 0)
-
 /* Success and failure values returned by pthdb callbacks.  */
 
 #define PDC_SUCCESS	PTHDB_SUCCESS
@@ -144,24 +140,6 @@ class aix_thread_target final : public target_ops
 
 static aix_thread_target aix_thread_ops;
 
-/* Address of the function that libpthread will call when libpthdebug
-   is ready to be initialized.  */
-
-static CORE_ADDR pd_brk_addr;
-
-/* Whether the current application is debuggable by pthdb.  */
-
-static int pd_able = 0;
-
-/* Whether a threaded application is being debugged.  */
-
-static int pd_active = 0;
-
-/* Whether the current architecture is 64-bit.  
-   Only valid when pd_able is true.  */
-
-static int arch64;
-
 /* Forward declarations for pthdb callbacks.  */
 
 static int pdc_symbol_addrs (pthdb_user_t, pthdb_symbol_t *, int);
@@ -191,9 +169,66 @@ static pthdb_callbacks_t pd_callbacks = {
   NULL
 };
 
-/* Current pthdb session.  */
+/* Aix variable structure.  */
+struct aix_thread_variables 
+{
+  /* Whether the current application is debuggable by pthdb.  */
+  int pd_able;
+
+  /* Whether a threaded application is being debugged.  */
+  int pd_active;
+
+  /* Current pthdb session.  */
+  pthdb_session_t pd_session;
+
+  /* Address of the function that libpthread will call when libpthdebug
+   is ready to be initialized.  */
+  CORE_ADDR pd_brk_addr;
+
+  /* Whether the current architecture is 64-bit.
+   Only valid when pd_able is true.  */
+  int arch64;
+};
 
-static pthdb_session_t pd_session;
+/* Key to our per-inferior data.  */
+static const registry<inferior>::key<aix_thread_variables>
+  aix_thread_variables_handle;
+
+/* Function to Get aix_thread_variables data.  */
+static struct aix_thread_variables*
+get_aix_thread_variables_data (struct inferior *inf)
+{
+  if (inf == NULL)
+    return NULL;
+
+  struct aix_thread_variables* data;
+
+  data = aix_thread_variables_handle.get (inf);
+  if (data == NULL)
+    data = aix_thread_variables_handle.emplace (inf);
+
+  return data;
+}
+
+/* Helper to get data for ptid in a function.  */
+
+static struct aix_thread_variables*
+get_thread_data_helper_for_ptid (ptid_t ptid)
+{
+  inferior *inf = find_inferior_ptid (current_inferior ()->process_target (),
+					ptid);
+  return get_aix_thread_variables_data (inf);
+}
+
+/* Helper to get data for pid in a function.  */
+
+static struct aix_thread_variables*
+get_thread_data_helper_for_pid (pid_t pid)
+{
+  inferior *inf = find_inferior_pid (current_inferior ()->process_target (),
+                                        pid);
+  return get_aix_thread_variables_data (inf);
+}
 
 /* Return a printable representation of pthdebug function return
    STATUS.  */
@@ -318,7 +353,7 @@ pid_to_prc (ptid_t *ptidp)
   ptid_t ptid;
 
   ptid = *ptidp;
-  if (PD_TID (ptid))
+  if (ptid.tid () != 0)
     *ptidp = ptid_t (ptid.pid ());
 }
 
@@ -389,6 +424,9 @@ pdc_read_regs (pthdb_user_t user_current_pid,
   double fprs[ppc_num_fprs];
   struct ptxsprs sprs64;
   struct ptsprs sprs32;
+  struct aix_thread_variables *data;
+  
+  data = get_thread_data_helper_for_pid (user_current_pid);
   
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, "pdc_read_regs tid=%d flags=%s\n",
@@ -397,7 +435,7 @@ pdc_read_regs (pthdb_user_t user_current_pid,
   /* General-purpose registers.  */
   if (flags & PTHDB_FLAG_GPRS)
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  if (!ptrace64aix (PTT_READ_GPRS, tid, 
 			    (unsigned long) gprs64, 0, NULL))
@@ -423,7 +461,7 @@ pdc_read_regs (pthdb_user_t user_current_pid,
   /* Special-purpose registers.  */
   if (flags & PTHDB_FLAG_SPRS)
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  if (!ptrace64aix (PTT_READ_SPRS, tid, 
 			    (unsigned long) &sprs64, 0, NULL))
@@ -456,6 +494,10 @@ pdc_write_regs (pthdb_user_t user_current_pid,
      this is needed, I have implemented what I think it should do,
      however this code is untested.  */
 
+  struct aix_thread_variables *data;
+  
+  data = get_thread_data_helper_for_pid (user_current_pid);
+
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, "pdc_write_regs tid=%d flags=%s\n",
 		(int) tid, hex_string (flags));
@@ -463,7 +505,7 @@ pdc_write_regs (pthdb_user_t user_current_pid,
   /* General-purpose registers.  */
   if (flags & PTHDB_FLAG_GPRS)
     {
-      if (arch64)
+      if (data->arch64)
 	ptrace64aix (PTT_WRITE_GPRS, tid, 
 		     (unsigned long) context->gpr, 0, NULL);
       else
@@ -479,7 +521,7 @@ pdc_write_regs (pthdb_user_t user_current_pid,
   /* Special-purpose registers.  */
   if (flags & PTHDB_FLAG_SPRS)
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  ptrace64aix (PTT_WRITE_SPRS, tid, 
 		       (unsigned long) &context->msr, 0, NULL);
@@ -508,14 +550,13 @@ pdc_read_data (pthdb_user_t user_current_pid, void *buf,
   /* This is needed to eliminate the dependency of current thread
      which is null so that thread reads the correct target memory.  */
   {
-    scoped_restore_current_thread restore_current_thread;
+    scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
     /* Before the first inferior is added, we pass inferior_ptid.pid ()
        from pd_enable () which is 0.  There is no need to switch threads
        during first initialisation.  In the rest of the callbacks the
        current thread needs to be correct.  */
     if (user_current_pid != 0)
-      switch_to_thread (current_inferior ()->process_target (),
-			ptid_t (user_current_pid));
+      inferior_ptid = ptid_t (user_current_pid);
     status = target_read_memory (addr, (gdb_byte *) buf, len);
   }
   ret = status == 0 ? PDC_SUCCESS : PDC_FAILURE;
@@ -639,39 +680,6 @@ pcmp (const void *p1v, const void *p2v)
   return p1->pthid < p2->pthid ? -1 : p1->pthid > p2->pthid;
 }
 
-/* iterate_over_threads() callback for counting GDB threads.
-
-   Do not count the main thread (whose tid is zero).  This matches
-   the list of threads provided by the pthreaddebug library, which
-   does not include that main thread either, and thus allows us
-   to compare the two lists.  */
-
-static int
-giter_count (struct thread_info *thread, void *countp)
-{
-  if (PD_TID (thread->ptid))
-    (*(int *) countp)++;
-  return 0;
-}
-
-/* iterate_over_threads() callback for accumulating GDB thread pids.
-
-   Do not include the main thread (whose tid is zero).  This matches
-   the list of threads provided by the pthreaddebug library, which
-   does not include that main thread either, and thus allows us
-   to compare the two lists.  */
-
-static int
-giter_accum (struct thread_info *thread, void *bufp)
-{
-  if (PD_TID (thread->ptid))
-    {
-      **(struct thread_info ***) bufp = thread;
-      (*(struct thread_info ***) bufp)++;
-    }
-  return 0;
-}
-
 /* ptid comparison function */
 
 static int
@@ -719,7 +727,10 @@ get_signaled_thread (int pid)
 		    sizeof (thrinf), &ktid, 1) != 1)
 	break;
 
-      if (thrinf.ti_cursig == SIGTRAP)
+      /* We also need to keep in mind Trap and interrupt or any
+         signal that needs to be handled in pd_update ().  */
+
+      if (thrinf.ti_cursig)
 	return thrinf.ti_tid;
     }
 
@@ -750,6 +761,11 @@ sync_threadlists (int pid)
   pthdb_pthread_t pdtid;
   pthread_t pthid;
   pthdb_tid_t tid;
+  process_stratum_target *proc_target
+            = current_inferior ()->process_target ();
+  thread_info  *tp;
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_pid (pid);
 
   /* Accumulate an array of libpthdebug threads sorted by pthread id.  */
 
@@ -759,11 +775,11 @@ sync_threadlists (int pid)
 
   for (cmd = PTHDB_LIST_FIRST;; cmd = PTHDB_LIST_NEXT)
     {
-      status = pthdb_pthread (pd_session, &pdtid, cmd);
+      status = pthdb_pthread (data->pd_session, &pdtid, cmd);
       if (status != PTHDB_SUCCESS || pdtid == PTHDB_INVALID_PTHREAD)
 	break;
 
-      status = pthdb_pthread_ptid (pd_session, pdtid, &pthid);
+      status = pthdb_pthread_ptid (data->pd_session, pdtid, &pthid);
       if (status != PTHDB_SUCCESS || pthid == PTHDB_INVALID_PTID)
 	continue;
 
@@ -780,7 +796,7 @@ sync_threadlists (int pid)
 
   for (pi = 0; pi < pcount; pi++)
     {
-      status = pthdb_pthread_tid (pd_session, pbuf[pi].pdtid, &tid);
+      status = pthdb_pthread_tid (data->pd_session, pbuf[pi].pdtid, &tid);
       if (status != PTHDB_SUCCESS)
 	tid = PTHDB_INVALID_TID;
       pbuf[pi].tid = tid;
@@ -790,10 +806,17 @@ sync_threadlists (int pid)
 
   /* Accumulate an array of GDB threads sorted by pid.  */
 
+  /* gcount is GDB thread count and pcount is pthreadlib thread count.  */
+
   gcount = 0;
-  iterate_over_threads (giter_count, &gcount);
+  for (thread_info *tp : all_threads (proc_target, ptid_t (pid)))
+    gcount++;
   g = gbuf = XNEWVEC (struct thread_info *, gcount);
-  iterate_over_threads (giter_accum, &g);
+  for (thread_info *tp : all_threads (proc_target, ptid_t (pid)))
+  {
+    **(struct thread_info ***) &g = tp;
+    (*(struct thread_info ***) &g)++;
+  }
   qsort (gbuf, gcount, sizeof *gbuf, gcmp);
 
   /* Apply differences between the two arrays to GDB's thread list.  */
@@ -810,8 +833,6 @@ sync_threadlists (int pid)
 	  priv->pdtid = pbuf[pi].pdtid;
 	  priv->tid = pbuf[pi].tid;
 
-	  process_stratum_target *proc_target
-	    = current_inferior ()->process_target ();
 	  thread = add_thread_with_info (proc_target,
 					 ptid_t (pid, 0, pbuf[pi].pthid),
 					 priv);
@@ -830,6 +851,23 @@ sync_threadlists (int pid)
 
 	  cmp_result = ptid_cmp (pptid, gptid);
 
+	  /* If there is only one thread then we need not make the main 
+	     thread look like a thread.  It can stay as a process. This
+	     is useful when we have multiple inferiors, but only one is
+	     threaded.  So we need not make the other inferiors with only
+	     main thread, look like a threaded one.  For example, Thread
+	     1.1, 1.2, 2.1, 3.1 exists then it is useful to skip this for
+	     loop for 2.1 and 3.1 leaving them as main process thread with
+	     a dummy priv set.  */
+
+	  if (pcount == 1 && gcount == 1)
+	  {
+	    aix_thread_info *priv = new aix_thread_info;
+	    tp = find_thread_ptid (proc_target, gptid);
+	    tp->priv.reset (priv);
+	    break;
+	  }
+
 	  if (cmp_result == 0)
 	    {
 	      aix_thread_info *priv = get_aix_thread_info (gbuf[gi]);
@@ -841,13 +879,28 @@ sync_threadlists (int pid)
 	    }
 	  else if (cmp_result > 0)
 	    {
-	      delete_thread (gbuf[gi]);
-	      gi++;
+	      /* This is to make the main process thread now look
+		 like a thread.  */
+
+	      if (gptid.is_pid () && gptid.pid () == pptid.pid ())
+	      {
+		thread_change_ptid (proc_target, gptid, pptid);
+		aix_thread_info *priv = new aix_thread_info;
+		priv->pdtid = pbuf[pi].pdtid;
+		priv->tid = pbuf[pi].tid;
+		tp = find_thread_ptid (proc_target, pptid);
+		tp->priv.reset (priv);
+		pi++;
+		gi++;
+	      }
+	      else
+	      {
+		delete_thread (gbuf[gi]);
+		gi++;
+	      }
 	    }
 	  else
 	    {
-	      process_stratum_target *proc_target
-		= current_inferior ()->process_target ();
 	      thread = add_thread (proc_target, pptid);
 
 	      aix_thread_info *priv = new aix_thread_info;
@@ -887,11 +940,14 @@ pd_update (int pid)
   ptid_t ptid;
   pthdb_tid_t tid;
   struct thread_info *thread = NULL;
+  struct aix_thread_variables *data;
 
-  if (!pd_active)
+  data = get_thread_data_helper_for_pid (pid);
+
+  if (!data->pd_active)
     return ptid_t (pid);
 
-  status = pthdb_session_update (pd_session);
+  status = pthdb_session_update (data->pd_session);
   if (status != PTHDB_SUCCESS)
     return ptid_t (pid);
 
@@ -918,15 +974,17 @@ static ptid_t
 pd_activate (int pid)
 {
   int status;
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_pid (pid);
 		
-  status = pthdb_session_init (pid, arch64 ? PEM_64BIT : PEM_32BIT,
+  status = pthdb_session_init (pid, data->arch64 ? PEM_64BIT : PEM_32BIT,
 			       PTHDB_FLAG_REGS, &pd_callbacks, 
-			       &pd_session);
+			       &data->pd_session);
   if (status != PTHDB_SUCCESS)
     {
       return ptid_t (pid);
     }
-  pd_active = 1;
+  data->pd_active = 1;
   return pd_update (pid);
 }
 
@@ -935,12 +993,15 @@ pd_activate (int pid)
 static void
 pd_deactivate (void)
 {
-  if (!pd_active)
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_ptid (inferior_ptid);
+
+  if (!data->pd_active)
     return;
-  pthdb_session_destroy (pd_session);
+  pthdb_session_destroy (data->pd_session);
   
   pid_to_prc (&inferior_ptid);
-  pd_active = 0;
+  data->pd_active = 0;
 }
 
 /* An object file has just been loaded.  Check whether the current
@@ -952,13 +1013,19 @@ pd_enable (void)
   int status;
   char *stub_name;
   struct bound_minimal_symbol ms;
+  struct aix_thread_variables *data;
+
+  if (!inferior_ptid.pid ())
+    return;
+  
+  data = get_thread_data_helper_for_ptid (inferior_ptid);
 
   /* Don't initialize twice.  */
-  if (pd_able)
+  if (data->pd_able)
     return;
 
   /* Check application word size.  */
-  arch64 = register_size (target_gdbarch (), 0) == 8;
+  data->arch64 = register_size (target_gdbarch (), 0) == 8;
 
   /* Check whether the application is pthreaded.  */
   stub_name = NULL;
@@ -972,13 +1039,13 @@ pd_enable (void)
   ms = lookup_minimal_symbol (stub_name, NULL, NULL);
   if (ms.minsym == NULL)
     return;
-  pd_brk_addr = ms.value_address ();
-  if (!create_thread_event_breakpoint (target_gdbarch (), pd_brk_addr))
+  data->pd_brk_addr = ms.value_address ();
+  if (!create_thread_event_breakpoint (target_gdbarch (), data->pd_brk_addr))
     return;
 
   /* Prepare for thread debugging.  */
   current_inferior ()->push_target (&aix_thread_ops);
-  pd_able = 1;
+  data->pd_able = 1; 
 
   /* If we're debugging a core file or an attached inferior, the
      pthread library may already have been initialized, so try to
@@ -991,28 +1058,27 @@ pd_enable (void)
 static void
 pd_disable (void)
 {
-  if (!pd_able)
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_ptid (inferior_ptid);
+
+  if (!data->pd_able)
     return;
-  if (pd_active)
+  if (data->pd_active)
     pd_deactivate ();
-  pd_able = 0;
+  data->pd_able = 0;
   current_inferior ()->unpush_target (&aix_thread_ops);
 }
 
 /* new_objfile observer callback.
 
    If OBJFILE is non-null, check whether a threaded application is
-   being debugged, and if so, prepare for thread debugging.
-
-   If OBJFILE is null, stop debugging threads.  */
+   being debugged, and if so, prepare for thread debugging.  */
 
 static void
 new_objfile (struct objfile *objfile)
 {
   if (objfile)
     pd_enable ();
-  else
-    pd_disable ();
 }
 
 /* Attach to process specified by ARGS.  */
@@ -1042,8 +1108,11 @@ aix_thread_target::resume (ptid_t ptid, int step, enum gdb_signal sig)
 {
   struct thread_info *thread;
   pthdb_tid_t tid[2];
+  struct aix_thread_variables *data;
+  
+  data = get_thread_data_helper_for_ptid (ptid);
 
-  if (!PD_TID (ptid))
+  if (!(ptid.tid () != 0))
     {
       scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
       
@@ -1065,7 +1134,7 @@ aix_thread_target::resume (ptid_t ptid, int step, enum gdb_signal sig)
 	       ptid.lwp ());
       tid[1] = 0;
 
-      if (arch64)
+      if (data->arch64)
 	ptrace64aix (PTT_CONTINUE, tid[0], (long long) 1,
 		     gdb_signal_to_host (sig), (PTRACE_TYPE_ARG5) tid);
       else
@@ -1082,6 +1151,7 @@ ptid_t
 aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
 			 target_wait_flags options)
 {
+  struct aix_thread_variables *data;
   {
     pid_to_prc (&ptid);
 
@@ -1095,8 +1165,10 @@ aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
      pid-only ptids.  */
   gdb_assert (ptid.is_pid ());
 
+  data = get_thread_data_helper_for_ptid (ptid);
+
   /* Check whether libpthdebug might be ready to be initialized.  */
-  if (!pd_active && status->kind () == TARGET_WAITKIND_STOPPED
+  if (!data->pd_active && status->kind () == TARGET_WAITKIND_STOPPED
       && status->sig () == GDB_SIGNAL_TRAP)
     {
       process_stratum_target *proc_target
@@ -1105,7 +1177,7 @@ aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
       struct gdbarch *gdbarch = regcache->arch ();
 
       if (regcache_read_pc (regcache)
-	  - gdbarch_decr_pc_after_break (gdbarch) == pd_brk_addr)
+	  - gdbarch_decr_pc_after_break (gdbarch) == data->pd_brk_addr)
 	return pd_activate (ptid.pid ());
     }
 
@@ -1229,18 +1301,20 @@ fetch_regs_user_thread (struct regcache *regcache, pthdb_pthread_t pdtid)
   ppc_gdbarch_tdep *tdep = gdbarch_tdep<ppc_gdbarch_tdep> (gdbarch);
   int status, i;
   pthdb_context_t ctx;
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_ptid (inferior_ptid);
 
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, 
 		"fetch_regs_user_thread %lx\n", (long) pdtid);
-  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_context (data->pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: fetch_registers: pthdb_pthread_context returned %s"),
 	   pd_status2str (status));
 
   /* General-purpose registers.  */
 
-  if (arch64)
+  if (data->arch64)
     supply_gprs64 (regcache, ctx.gpr);
   else
     for (i = 0; i < ppc_num_gprs; i++)
@@ -1253,7 +1327,7 @@ fetch_regs_user_thread (struct regcache *regcache, pthdb_pthread_t pdtid)
 
   /* Special registers.  */
 
-  if (arch64)
+  if (data->arch64)
     supply_sprs64 (regcache, ctx.iar, ctx.msr, ctx.cr, ctx.lr, ctx.ctr,
 			     ctx.xer, ctx.fpscr);
   else
@@ -1288,18 +1362,21 @@ fetch_regs_kernel_thread (struct regcache *regcache, int regno,
   struct ptxsprs sprs64;
   struct ptsprs sprs32;
   int i;
+  struct aix_thread_variables *data;
+  
+  data = get_thread_data_helper_for_ptid (regcache->ptid ());
 
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog,
 		"fetch_regs_kernel_thread tid=%lx regno=%d arch64=%d\n",
-		(long) tid, regno, arch64);
+		(long) tid, regno, data->arch64);
 
   /* General-purpose registers.  */
   if (regno == -1
       || (tdep->ppc_gp0_regnum <= regno
 	  && regno < tdep->ppc_gp0_regnum + ppc_num_gprs))
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  if (!ptrace64aix (PTT_READ_GPRS, tid, 
 			    (unsigned long) gprs64, 0, NULL))
@@ -1331,7 +1408,7 @@ fetch_regs_kernel_thread (struct regcache *regcache, int regno,
 
   if (regno == -1 || special_register_p (gdbarch, regno))
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  if (!ptrace64aix (PTT_READ_SPRS, tid, 
 			    (unsigned long) &sprs64, 0, NULL))
@@ -1363,7 +1440,7 @@ aix_thread_target::fetch_registers (struct regcache *regcache, int regno)
   struct thread_info *thread;
   pthdb_tid_t tid;
 
-  if (!PD_TID (regcache->ptid ()))
+  if (!(regcache->ptid ().tid () != 0))
     beneath ()->fetch_registers (regcache, regno);
   else
     {
@@ -1511,6 +1588,8 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
   pthdb_context_t ctx;
   uint32_t int32;
   uint64_t int64;
+  struct aix_thread_variables *data;
+  data = get_thread_data_helper_for_ptid (inferior_ptid);
 
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, 
@@ -1518,7 +1597,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
 
   /* Retrieve the thread's current context for its non-register
      values.  */
-  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_context (data->pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: store_registers: pthdb_pthread_context returned %s"),
 	   pd_status2str (status));
@@ -1528,7 +1607,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
   for (i = 0; i < ppc_num_gprs; i++)
     if (REG_VALID == regcache->get_register_status (tdep->ppc_gp0_regnum + i))
       {
-	if (arch64)
+	if (data->arch64)
 	  {
 	    regcache->raw_collect (tdep->ppc_gp0_regnum + i, (void *) &int64);
 	    ctx.gpr[i] = int64;
@@ -1545,7 +1624,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
     fill_fprs (regcache, ctx.fpr);
 
   /* Special registers (always kept in ctx as 64 bits).  */
-  if (arch64)
+  if (data->arch64)
     {
       fill_sprs64 (regcache, &ctx.iar, &ctx.msr, &ctx.cr, &ctx.lr, &ctx.ctr,
 			     &ctx.xer, &ctx.fpscr);
@@ -1576,7 +1655,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
 	ctx.fpscr = tmp_fpscr;
     }
 
-  status = pthdb_pthread_setcontext (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_setcontext (data->pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: store_registers: "
 	     "pthdb_pthread_setcontext returned %s"),
@@ -1602,6 +1681,9 @@ store_regs_kernel_thread (const struct regcache *regcache, int regno,
   double fprs[ppc_num_fprs];
   struct ptxsprs sprs64;
   struct ptsprs  sprs32;
+  struct aix_thread_variables *data;
+  
+  data = get_thread_data_helper_for_ptid (regcache->ptid ());
 
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, 
@@ -1613,7 +1695,7 @@ store_regs_kernel_thread (const struct regcache *regcache, int regno,
       || (tdep->ppc_gp0_regnum <= regno
 	  && regno < tdep->ppc_gp0_regnum + ppc_num_fprs))
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  /* Pre-fetch: some regs may not be in the cache.  */
 	  ptrace64aix (PTT_READ_GPRS, tid, (unsigned long) gprs64, 0, NULL);
@@ -1646,7 +1728,7 @@ store_regs_kernel_thread (const struct regcache *regcache, int regno,
 
   if (regno == -1 || special_register_p (gdbarch, regno))
     {
-      if (arch64)
+      if (data->arch64)
 	{
 	  /* Pre-fetch: some registers won't be in the cache.  */
 	  ptrace64aix (PTT_READ_SPRS, tid, 
@@ -1703,7 +1785,7 @@ aix_thread_target::store_registers (struct regcache *regcache, int regno)
   struct thread_info *thread;
   pthdb_tid_t tid;
 
-  if (!PD_TID (regcache->ptid ()))
+  if (!(regcache->ptid ().tid () != 0))
     beneath ()->store_registers (regcache, regno);
   else
     {
@@ -1741,7 +1823,7 @@ aix_thread_target::mourn_inferior ()
 {
   target_ops *beneath = this->beneath ();
 
-  pd_deactivate ();
+  pd_disable ();
   beneath->mourn_inferior ();
 }
 
@@ -1750,7 +1832,7 @@ aix_thread_target::mourn_inferior ()
 bool
 aix_thread_target::thread_alive (ptid_t ptid)
 {
-  if (!PD_TID (ptid))
+  if (!(ptid.tid () != 0))
     return beneath ()->thread_alive (ptid);
 
   /* We update the thread list every time the child stops, so all
@@ -1766,7 +1848,7 @@ aix_thread_target::thread_alive (ptid_t ptid)
 std::string
 aix_thread_target::pid_to_str (ptid_t ptid)
 {
-  if (!PD_TID (ptid))
+  if (!(ptid.tid () != 0))
     return beneath ()->pid_to_str (ptid);
 
   return string_printf (_("Thread %s"), pulongest (ptid.tid ()));
@@ -1786,8 +1868,11 @@ aix_thread_target::extra_thread_info (struct thread_info *thread)
   pthdb_detachstate_t detachstate;
   int cancelpend;
   static char *ret = NULL;
+  struct aix_thread_variables *data;
+
+  data = get_thread_data_helper_for_ptid (thread->ptid);
 
-  if (!PD_TID (thread->ptid))
+  if (!(thread->ptid.tid () != 0))
     return NULL;
 
   string_file buf;
@@ -1800,24 +1885,24 @@ aix_thread_target::extra_thread_info (struct thread_info *thread)
     /* i18n: Like "thread-identifier %d, [state] running, suspended" */
     buf.printf (_("tid %d"), (int)tid);
 
-  status = pthdb_pthread_state (pd_session, pdtid, &state);
+  status = pthdb_pthread_state (data->pd_session, pdtid, &state);
   if (status != PTHDB_SUCCESS)
     state = PST_NOTSUP;
   buf.printf (", %s", state2str (state));
 
-  status = pthdb_pthread_suspendstate (pd_session, pdtid, 
+  status = pthdb_pthread_suspendstate (data->pd_session, pdtid, 
 				       &suspendstate);
   if (status == PTHDB_SUCCESS && suspendstate == PSS_SUSPENDED)
     /* i18n: Like "Thread-Id %d, [state] running, suspended" */
     buf.printf (_(", suspended"));
 
-  status = pthdb_pthread_detachstate (pd_session, pdtid, 
+  status = pthdb_pthread_detachstate (data->pd_session, pdtid, 
 				      &detachstate);
   if (status == PTHDB_SUCCESS && detachstate == PDS_DETACHED)
     /* i18n: Like "Thread-Id %d, [state] running, detached" */
     buf.printf (_(", detached"));
 
-  pthdb_pthread_cancelpend (pd_session, pdtid, &cancelpend);
+  pthdb_pthread_cancelpend (data->pd_session, pdtid, &cancelpend);
   if (status == PTHDB_SUCCESS && cancelpend)
     /* i18n: Like "Thread-Id %d, [state] running, cancel pending" */
     buf.printf (_(", cancel pending"));
diff --git a/gdb/solib-aix.c b/gdb/solib-aix.c
index f483f54de13..671c17cba46 100644
--- a/gdb/solib-aix.c
+++ b/gdb/solib-aix.c
@@ -618,6 +618,16 @@ solib_aix_bfd_open (const char *pathname)
       if (member_name == bfd_get_filename (object_bfd.get ()))
 	break;
 
+      std::string s = bfd_get_filename (object_bfd.get ());
+
+      /* For every inferior after first int bfd system we 
+	 will have the pathname instead of the member name
+	 registered. Hence the below condition exists.  */
+
+      if (s.find ('(') != std::string::npos
+	  && s.find (member_name) != std::string::npos)
+	return object_bfd; 
+
       object_bfd = gdb_bfd_openr_next_archived_file (archive_bfd.get (),
 						     object_bfd.get ());
     }
-- 
2.31.1