old-cross-binutils/gdb/testsuite/gdb.threads/thread-specific-bp.c

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PR gdb/11568 - delete thread-specific breakpoints on thread exit PR gdb/11568 is about thread-specific breakpoints being left behind when the corresponding thread exits. Currently: (gdb) b start thread 2 Breakpoint 3 at 0x400614: file thread-specific-bp.c, line 23. (gdb) b end Breakpoint 4 at 0x40061f: file thread-specific-bp.c, line 29. (gdb) c Continuing. [Thread 0x7ffff7fcb700 (LWP 14925) exited] [Switching to Thread 0x7ffff7fcc740 (LWP 14921)] Breakpoint 4, end () at thread-specific-bp.c:29 29 } (gdb) info threads Id Target Id Frame * 1 Thread 0x7ffff7fcc740 (LWP 14921) "thread-specific" end () at thread-specific-bp.c:29 (gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 0x0000000000400614 in start at thread-specific-bp.c:23 breakpoint already hit 1 time 3 breakpoint keep y 0x0000000000400614 in start at thread-specific-bp.c:23 thread 2 stop only in thread 2 4 breakpoint keep y 0x000000000040061f in end at thread-specific-bp.c:29 breakpoint already hit 1 time Note that the thread-specific breakpoint 3 stayed around, even though thread 2 is gone. There's no way that breakpoint can trigger again (*), so the PR argues that the breakpoint should just be removed, like local watchpoints. I'm ambivalent on this -- it could be reasonable to disable the breakpoint (kind of like breakpoint in shared library code when the DSO is unloaded), so the user could still use it as visual template for creating other breakpoints (copy/paste command lists, etc.), or we could have a way to change to which thread a breakpoint applies. But, several people pushed this direction, and I don't plan on arguing... (*) - actually, there is ... thread numbers are reset on "run", so the user could do "break foo thread 2", "run", and expect the breakpoint to hit again on the second thread. But given gdb's thread numbering can't really be stable, that'd only work sufficiently well for thread 1, so we'd better call it unsupported. So with the patch, whenever a thread is deleted from GDB's list, GDB goes through the thread-specific breakpoints and deletes corresponding breakpoints. Since this is user-visible, GDB prints out: Thread-specific breakpoint 3 deleted - thread 2 is gone. And of course, we end up with: (gdb) info breakpoints Num Type Disp Enb Address What 2 breakpoint keep y 0x0000000000400614 in start at thread-specific-bp.c:23 breakpoint already hit 1 time 4 breakpoint keep y 0x000000000040061f in end at thread-specific-bp.c:29 breakpoint already hit 1 time 2013-09-17 Muhammad Waqas <mwaqas@codesourcery.com> Pedro Alves <palves@redhat.com> PR gdb/11568 * breakpoint.c (remove_threaded_breakpoints): New function. (_initialize_breakpoint): Attach remove_threaded_breakpoints as thread_exit observer. 2013-09-17 Muhammad Waqas <mwaqas@codesourccery.com> Jan Kratochvil <jan.kartochvil@redhat.com> Pedro Alves <palves@redhat.com> PR gdb/11568 * gdb.thread/thread-specific-bp.c: New file. * gdb.thread/thread-specific-bp.exp: New file.
2013-09-17 19:32:47 +00:00
/* This testcase is part of GDB, the GNU debugger.
Copyright 2013 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <pthread.h>
static void *
start (void *arg)
{
return NULL;
}
static void
end (void)
{
}
int
main (void)
{
pthread_t thread;
pthread_create (&thread, NULL, start, NULL);
pthread_join (thread, NULL);
end ();
return 0;
}