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b73715df01
When debugging any of the testcases added by this commit, which do a vfork in a thread with "set follow-fork-mode child" + "set detach-on-fork on", we run into this assertion: ... src/gdb/nat/x86-linux-dregs.c:146: internal-error: \ void x86_linux_update_debug_registers(lwp_info*): \ Assertion `lwp_is_stopped (lwp)' failed. ... The assert is caused by the following: the vfork-child exit or exec event is handled by handle_vfork_child_exec_or_exit, which calls target_detach to detach from the vfork parent. During target_detach we call linux_nat_target::detach, which: #1 - stops all the threads #2 - waits for all the threads to be stopped #3 - detaches all the threads However, during the second step we run into this code in stop_wait_callback: ... /* If this is a vfork parent, bail out, it is not going to report any SIGSTOP until the vfork is done with. */ if (inf->vfork_child != NULL) return 0; ... and we don't wait for the threads to be stopped, which results in this assert in x86_linux_update_debug_registers triggering during the third step: ... gdb_assert (lwp_is_stopped (lwp)); ... The fix is to reset the vfork parent's vfork_child field before calling target_detach in handle_vfork_child_exec_or_exit. There's already similar code for the other paths handled by handle_vfork_child_exec_or_exit, so this commit refactors the code a bit so that all paths share the same code. The new tests cover both a vfork child exiting, and a vfork child execing, since both cases would trigger the assertion. The new testcases also exercise following the vfork children with "set detach-on-fork off", since it doesn't seem to be tested anywhere. Tested on x86_64-linux, using native and native-gdbserver. gdb/ChangeLog: 2019-04-18 Tom de Vries <tdevries@suse.de> Pedro Alves <palves@redhat.com> PR gdb/24454 * infrun.c (handle_vfork_child_exec_or_exit): Reset vfork parent's vfork_child field before calling target_detach. gdb/testsuite/ChangeLog: 2019-04-18 Tom de Vries <tdevries@suse.de> Pedro Alves <palves@redhat.com> PR gdb/24454 * gdb.threads/vfork-follow-child-exec.c: New file. * gdb.threads/vfork-follow-child-exec.exp: New file. * gdb.threads/vfork-follow-child-exit.c: New file. * gdb.threads/vfork-follow-child-exit.exp: New file.
53 lines
1.2 KiB
C
53 lines
1.2 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 <unistd.h>
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#include <pthread.h>
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static void *
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f (void *arg)
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{
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int res = vfork ();
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if (res == -1)
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{
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perror ("vfork");
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return NULL;
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}
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else if (res == 0)
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{
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/* Child. */
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_exit (0);
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}
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else
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{
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/* Parent. */
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return NULL;
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}
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}
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int
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main (void)
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{
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pthread_t tid;
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pthread_create (&tid, NULL, f, NULL);
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pthread_join (tid, NULL);
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return 0;
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}
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