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Fix AIX thr!= NULL assertion failure during fork.

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In AIX, while we followed the child process and detach on fork was on we hit thr!= NULL assertion failure.

The reason for the same was GDB core trying to switch to a child thread with tid not set that does not
exist, since child's ptid was changed to ptid_t (pid, 0, tid) in sync_threadlists() as it was threaded.

The way this happened was when a new child process is born, its object file will be loaded, calling the new_objfile ()
in aix-thread.c file from clone_program_space, which is
called from within follow_fork_inferior. Therefore it end ups syncing threadlists via pd_update ().

This patch is a fix for the same where pd_update () is called in the wait () or in update_thread_list() hook only.
This commit is contained in:
Aditya Vidyadhar Kamath
2023-11-22 10:13:35 -06:00
committed by Ulrich Weigand
parent 03893ce67b
commit 10a0a5e239
1 changed files with 20 additions and 8 deletions
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28
gdb/aix-thread.c
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@@ -136,6 +136,8 @@ public:
const char *extra_thread_info (struct thread_info *) override;
ptid_t get_ada_task_ptid (long lwp, ULONGEST thread) override;
void update_thread_list () override;
};
static aix_thread_target aix_thread_ops;
@@ -1015,7 +1017,7 @@ pd_update (pid_t pid)
If successful and there exists and we can find an event thread, return a ptid
for that thread. Otherwise, return a ptid-only ptid using PID. */
static ptid_t
static void
pd_activate (pid_t pid)
{
int status;
@@ -1030,9 +1032,24 @@ pd_activate (pid_t pid)
return ptid_t (pid);
}
data->pd_active = 1;
return pd_update (pid);
return;
}
/* AIX implementation of update_thread_list. */
void
aix_thread_target::update_thread_list ()
{
for (inferior *inf : all_inferiors ())
{
if (inf->pid == 0)
continue;
pd_update (inf->pid);
}
}
/* An object file has just been loaded. Check whether the current
application is pthreaded, and if so, prepare for thread debugging. */
@@ -1077,11 +1094,6 @@ pd_enable (inferior *inf)
current_inferior ()->push_target (&aix_thread_ops);
data->pd_able = 1;
/* When attaching / handling fork child, don't try activating
thread debugging until we know about all shared libraries. */
if (inf->in_initial_library_scan)
return;
/* If we're debugging a core file or an attached inferior, the
pthread library may already have been initialized, so try to
activate thread debugging. */
@@ -1216,7 +1228,7 @@ aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
if (regcache_read_pc (regcache)
- gdbarch_decr_pc_after_break (gdbarch) == data->pd_brk_addr)
return pd_activate (ptid.pid ());
pd_activate (ptid.pid ());
}
return pd_update (ptid.pid ());