7868401b7b
This patch addresses "fork:Interrupted system call" (or wait:) failures
in gdb.threads/forking-threads-plus-breakpoint.exp.
The test program spawns ten threads, each of which do ten fork/waitpid
sequences. The cause of the problem was that when one of the fork
children exited before the corresponding fork parent could initiate its
waitpid for that child, a SIGCHLD and/or SIGSTOP was delivered and
interrupted a fork or waitpid in another thread.
The fix was to wrap the system calls in a loop to retry the call if
it was interrupted, like:
do
{
pid = fork ();
}
while (pid == -1 && errno == EINTR);
Since this is a Linux-only test I figure it is OK to use errno and EINTR.
I tried a number of alternative fixes using SIG_IGN, SA_RESTART,
pthread_sigblock, and bsd_signal, but none of these worked as well.
Tested on Nios II Linux target with x86 Linux host.
gdb/testsuite/ChangeLog:
2016-03-16 Don Breazeal <donb@codesourcery.com>
* gdb.threads/forking-threads-plus-breakpoint.c (thread_forks):
Retry fork and waitpid on interrupted system call errors.
* gdb.threads/forking-threads-plus-breakpoint.exp: (do_test):
Use with_timeout_factor to increase timeout to 90.
149 lines
3 KiB
C
149 lines
3 KiB
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015-2016 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 <assert.h>
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#include <pthread.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <errno.h>
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/* Number of threads. Each thread continuously spawns a fork and wait
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for it. If we have another thread continuously start a step over,
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gdbserver should end up finding new forks while suspending
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threads. */
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#define NTHREADS 10
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pthread_t threads[NTHREADS];
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pthread_barrier_t barrier;
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#define NFORKS 10
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/* Used to create a conditional breakpoint that always fails. */
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volatile int zero;
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static void *
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thread_forks (void *arg)
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{
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int i;
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pthread_barrier_wait (&barrier);
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for (i = 0; i < NFORKS; i++)
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{
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pid_t pid;
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do
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{
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pid = fork ();
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}
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while (pid == -1 && errno == EINTR);
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if (pid > 0)
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{
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int status;
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/* Parent. */
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do
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{
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pid = waitpid (pid, &status, 0);
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}
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while (pid == -1 && errno == EINTR);
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if (pid == -1)
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{
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perror ("wait");
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exit (1);
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}
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if (!WIFEXITED (status))
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{
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printf ("Unexpected wait status 0x%x from child %d\n",
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status, pid);
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}
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}
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else if (pid == 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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perror ("fork");
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exit (1);
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}
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}
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}
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/* Set this to tell the thread_breakpoint thread to exit. */
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volatile int break_out;
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static void *
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thread_breakpoint (void *arg)
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{
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pthread_barrier_wait (&barrier);
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while (!break_out)
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{
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usleep (1); /* set break here */
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}
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return NULL;
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}
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pthread_barrier_t barrier;
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int
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main (void)
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{
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int i;
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int ret;
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pthread_t bp_thread;
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/* Don't run forever. */
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alarm (180);
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pthread_barrier_init (&barrier, NULL, NTHREADS + 1);
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/* Start the threads that constantly fork. */
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for (i = 0; i < NTHREADS; i++)
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{
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ret = pthread_create (&threads[i], NULL, thread_forks, NULL);
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assert (ret == 0);
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}
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/* Start the thread that constantly hit a conditional breakpoint
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that needs to be stepped over. */
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ret = pthread_create (&bp_thread, NULL, thread_breakpoint, NULL);
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assert (ret == 0);
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/* Wait for forking to stop. */
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for (i = 0; i < NTHREADS; i++)
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{
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ret = pthread_join (threads[i], NULL);
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assert (ret == 0);
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}
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break_out = 1;
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pthread_join (bp_thread, NULL);
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assert (ret == 0);
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return 0;
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}
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