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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug threads/28065] FAIL:
 gdb.threads/access-mem-running-thread-exit.exp: all-stop: access mem (print
 global_var after writing again, inf=1, iter=354)
Date: Fri, 09 Jul 2021 13:33:30 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D28065

--- Comment #12 from Tom de Vries <vries at gcc dot gnu.org> ---
I updated the test-case to remove "set print thread-events off".

Also I moved the debug statements related to the /mem fp to a separate debug
category: lin-lwp-mem, enabled it in the test-case, and verified that the
problem still reproduced.

Changes available at
https://github.com/vries/gdb/commits/access-mem-running-thread-exit-v2 .

I got the following log:
...
[linux-nat] linux_proc_xfer_memory_partial_pid: opening
/proc/14678/task/19075/mem failed: No such file or directory (2)^M
^M
[linux-nat] linux_proc_xfer_memory_partial_pid: opened fd 13 for
/proc/14678/task/19285/mem^M
^M
[linux-nat] linux_proc_xfer_memory_partial_pid: accessing fd 13 for pid 192=
85
got EOF^M
^M
[linux-nat] linux_proc_xfer_memory_partial_pid: fd 13 for
/proc/14678/task/19285/mem^M
^M
[linux-nat] linux_proc_xfer_memory_partial_pid: accessing fd 13 for pid 190=
75
got EOF^M
^M
[linux-nat] linux_proc_xfer_memory_partial_pid: fd 13 for
/proc/14678/task/19285/mem^M
^M
Cannot access memory at address 0x601070^M
(gdb) [LWP 19287 exited]^M
...

I noticed that we get EOF twice, and the second time try for the same file.

This led me to the following:
...
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index f206b874929..14892a4ee2a 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -3907,6 +3907,7 @@ linux_proc_xfer_memory_partial_pid (ptid_t ptid,
     {
       linux_nat_debug_printf ("accessing fd %d for pid %ld got EOF\n",
                              fd, ptid.lwp ());
+      last_proc_mem_file.close ();
     }

   return ret;
...

And this fixed the failure: I managed to run the test-case for half an hour
without triggering the FAIL.

I don't understand things well enough to say whether this is a proper fix.

--=20
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