glibc/malloc/tst-mallocfork2.c

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/* Test case for async-signal-safe fork (with respect to malloc).
Copyright (C) 2016-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB. If
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
2019-09-07 05:40:42 +00:00
not, see <https://www.gnu.org/licenses/>. */
/* This test will fail if the process is multi-threaded because we
only have an async-signal-safe fork in the single-threaded case
(where we skip acquiring the malloc heap locks).
This test only checks async-signal-safety with regards to malloc;
other, more rarely-used glibc subsystems could have locks which
still make fork unsafe, even in single-threaded processes. */
#include <errno.h>
#include <sched.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <array_length.h>
#include <support/check.h>
#include <support/support.h>
#include <support/xthread.h>
#include <support/xunistd.h>
/* How many malloc objects to keep arond. */
enum { malloc_objects = 1009 };
/* The maximum size of an object. */
enum { malloc_maximum_size = 70000 };
/* How many iterations the test performs before exiting. */
enum { iterations = 10000 };
/* Barrier for synchronization with the processes sending SIGUSR1
signals, to make it more likely that the signals arrive during a
fork/free/malloc call. */
static struct { pthread_barrier_t barrier; } *shared;
/* Set to 1 if SIGUSR1 is received. Used to detect a signal during
fork/free/malloc. */
static volatile sig_atomic_t sigusr1_received;
/* Periodically set to 1, to indicate that the process is making
progress. Checked by liveness_signal_handler. */
static volatile sig_atomic_t progress_indicator = 1;
/* Set to 1 if an error occurs in the signal handler. */
static volatile sig_atomic_t error_indicator = 0;
static void
sigusr1_handler (int signo)
{
sigusr1_received = 1;
/* Perform a fork with a trivial subprocess. */
pid_t pid = fork ();
if (pid == -1)
{
write_message ("error: fork\n");
error_indicator = 1;
return;
}
if (pid == 0)
_exit (0);
int status;
int ret = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
if (ret < 0)
{
write_message ("error: waitpid\n");
error_indicator = 1;
return;
}
if (status != 0)
{
write_message ("error: unexpected exit status from subprocess\n");
error_indicator = 1;
return;
}
}
static void
liveness_signal_handler (int signo)
{
if (progress_indicator)
progress_indicator = 0;
else
write_message ("warning: process seems to be stuck\n");
}
/* Send SIGNO to the parent process. If SLEEP, wait a second between
signals, otherwise use barriers to delay sending signals. */
static void
__attribute__ ((noreturn))
signal_sender (int signo, bool sleep)
{
pid_t target = getppid ();
while (true)
{
if (!sleep)
xpthread_barrier_wait (&shared->barrier);
if (kill (target, signo) != 0)
{
dprintf (STDOUT_FILENO, "error: kill: %m\n");
abort ();
}
if (sleep)
usleep (1 * 1000 * 1000);
else
xpthread_barrier_wait (&shared->barrier);
}
}
/* Children processes. */
static pid_t sigusr1_sender_pids[5] = { 0 };
static pid_t sigusr2_sender_pid = 0;
static void
kill_children (void)
{
for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
if (sigusr1_sender_pids[i] > 0)
kill (sigusr1_sender_pids[i], SIGKILL);
if (sigusr2_sender_pid > 0)
kill (sigusr2_sender_pid, SIGKILL);
}
static int
do_test (void)
{
atexit (kill_children);
/* shared->barrier is initialized along with sigusr1_sender_pids
below. */
shared = support_shared_allocate (sizeof (*shared));
struct sigaction action =
{
.sa_handler = sigusr1_handler,
};
sigemptyset (&action.sa_mask);
if (sigaction (SIGUSR1, &action, NULL) != 0)
{
printf ("error: sigaction: %m");
return 1;
}
action.sa_handler = liveness_signal_handler;
if (sigaction (SIGUSR2, &action, NULL) != 0)
{
printf ("error: sigaction: %m");
return 1;
}
sigusr2_sender_pid = xfork ();
if (sigusr2_sender_pid == 0)
signal_sender (SIGUSR2, true);
/* Send SIGUSR1 signals from several processes. Hopefully, one
signal will hit one of the critical functions. Use a barrier to
avoid sending signals while not running fork/free/malloc. */
{
pthread_barrierattr_t attr;
xpthread_barrierattr_init (&attr);
xpthread_barrierattr_setpshared (&attr, PTHREAD_PROCESS_SHARED);
xpthread_barrier_init (&shared->barrier, &attr,
array_length (sigusr1_sender_pids) + 1);
xpthread_barrierattr_destroy (&attr);
}
for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
{
sigusr1_sender_pids[i] = xfork ();
if (sigusr1_sender_pids[i] == 0)
signal_sender (SIGUSR1, false);
}
void *objects[malloc_objects] = {};
unsigned int fork_signals = 0;
unsigned int free_signals = 0;
unsigned int malloc_signals = 0;
unsigned seed = 1;
for (int i = 0; i < iterations; ++i)
{
progress_indicator = 1;
int slot = rand_r (&seed) % malloc_objects;
size_t size = rand_r (&seed) % malloc_maximum_size;
/* Occasionally do a fork first, to catch deadlocks there as
well (see bug 24161). */
bool do_fork = (rand_r (&seed) % 7) == 0;
xpthread_barrier_wait (&shared->barrier);
if (do_fork)
{
sigusr1_received = 0;
pid_t pid = xfork ();
if (sigusr1_received)
++fork_signals;
if (pid == 0)
_exit (0);
int status;
int ret = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
if (ret < 0)
FAIL_EXIT1 ("waitpid: %m");
TEST_COMPARE (status, 0);
}
sigusr1_received = 0;
free (objects[slot]);
if (sigusr1_received)
++free_signals;
sigusr1_received = 0;
objects[slot] = malloc (size);
if (sigusr1_received)
++malloc_signals;
xpthread_barrier_wait (&shared->barrier);
if (objects[slot] == NULL || error_indicator != 0)
{
printf ("error: malloc: %m\n");
for (size_t i = 0; i < array_length (sigusr1_sender_pids); ++i)
kill (sigusr1_sender_pids[i], SIGKILL);
kill (sigusr2_sender_pid, SIGKILL);
return 1;
}
}
/* Clean up allocations. */
for (int slot = 0; slot < malloc_objects; ++slot)
free (objects[slot]);
printf ("info: signals received during fork: %u\n", fork_signals);
printf ("info: signals received during free: %u\n", free_signals);
printf ("info: signals received during malloc: %u\n", malloc_signals);
/* Do not destroy the barrier because of the SIGKILL above, which
may have left the barrier in an inconsistent state. */
support_shared_free (shared);
return 0;
}
#define TIMEOUT 100
#include <support/test-driver.c>