d8c06f22a3
It was observed that in a multi-threaded application on GNU/Linux, that if the user has set the SIGSTOP to be pass (using GDB's handle command) then the inferior would hang upon hitting a breakpoint. What happens is that when a thread hits the breakpoint GDB tries to stop all of the other threads by sending them a SIGSTOP and setting the stop_requested flag in the target_ops structure - this can be seen in infrun.c:stop_all_threads. GDB then waits for all of the other threads to stop. When the SIGSTOP event arrives we eventually end up in linux-nat.c:linux_nat_filter_event, which has the job of deciding if the event we're looking at (the SIGSTOP arriving in this case) is something that should be reported back to the core of GDB. One of the final actions of this function is to check if we stopped due to a signal, and if we did, and the signal has been set to 'pass' by the user then we ignore the event and resume the thread. This code already has some conditions in place that mean the event is reported to GDB even if the signal is in the set of signals to be passed to the inferior. In this commit I extend this condition such that: If the signal is a SIGSTOP, and the thread's stop_requested flag is set (indicating we're waiting for the thread to stop with a SIGSTOP) then we should report this SIGSTOP to GDB and not pass it to the inferior. With this change in place the test now passes. Regression tested on x86-64 GNU/Linux with no regressions. gdb/ChangeLog: * linux-nat.c (linux_nat_filter_event): Don't ignore SIGSTOP if we have just sent the thread a SIGSTOP and are waiting for it to arrive. gdb/testsuite/ChangeLog: * gdb.threads/stop-with-handle.c: New file. * gdb.threads/stop-with-handle.exp: New file.
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2019 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <pthread.h>
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#include <unistd.h>
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/* A place to record the thread. */
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pthread_t the_thread;
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/* The worker thread just spins forever. */
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void*
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thread_worker (void *payload)
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{
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while (1)
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{
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sleep (1);
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}
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return NULL;
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}
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/* Create a worker thread. */
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int
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spawn_thread ()
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{
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if (pthread_create (&the_thread, NULL, thread_worker, NULL))
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{
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fprintf (stderr, "Unable to create thread.\n");
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return 0;
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}
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return 1;
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}
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/* A place for GDB to place a breakpoint. */
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void __attribute__((used))
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breakpt ()
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{
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/* Nothing. */
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}
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/* Create a worker thread that just spins forever, then enter a loop
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periodically calling the BREAKPT function. */
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int
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main()
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{
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/* Ensure we stop if GDB crashes and DejaGNU fails to kill us. */
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alarm (10);
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spawn_thread ();
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while (1)
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{
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sleep (1);
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breakpt ();
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}
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return 0;
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}
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