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[PATCH 5/5] rt: Set shm_open as a non cancellation point (BZ #18243)
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 22 Aug 2016 11:27:33 -0300
- Subject: [PATCH 5/5] rt: Set shm_open as a non cancellation point (BZ #18243)
- Authentication-results: sourceware.org; auth=none
- References: <1471876053-780-1-git-send-email-adhemerval.zanella@linaro.org>
This patch changes shm_open to not act as a cancellation point.
Cancellation is disable at start and reenable in function exit.
It fixes BZ #18243.
Tested on x86_64 and i686.
[BZ #18243]
* rt/Makefile (test): Add tst-shm-cancel.
* rt/tst-shm-cancel.c: New file.
* sysdeps/posix/shm_open.c: Disable asynchronous cancellation.
---
rt/Makefile | 2 +-
rt/tst-shm-cancel.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++
sysdeps/posix/shm_open.c | 7 +++
3 files changed, 143 insertions(+), 1 deletion(-)
create mode 100644 rt/tst-shm-cancel.c
diff --git a/rt/Makefile b/rt/Makefile
index cfa6837..7593b11 100644
--- a/rt/Makefile
+++ b/rt/Makefile
@@ -53,7 +53,7 @@ tests := tst-shm tst-clock tst-clock_nanosleep tst-timer tst-timer2 \
tst-timer3 tst-timer4 tst-timer5 \
tst-cpuclock1 tst-cpuclock2 \
tst-cputimer1 tst-cputimer2 tst-cputimer3 \
- tst-clock2
+ tst-clock2 tst-shm-cancel
extra-libs := librt
extra-libs-others := $(extra-libs)
diff --git a/rt/tst-shm-cancel.c b/rt/tst-shm-cancel.c
new file mode 100644
index 0000000..de70c1a
--- /dev/null
+++ b/rt/tst-shm-cancel.c
@@ -0,0 +1,135 @@
+/* Test for shm_open cancellation handling: BZ #18243.
+ Copyright (C) 2016 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; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <pthread.h>
+#include <sys/mman.h>
+#include <semaphore.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+
+static sem_t sem; /* Use to sync with thread start. */
+volatile int thread_ret;
+static const char shm_name[] = "/glibc-shm_open-cancel";
+
+static void
+remove_shm (int status, void *arg)
+{
+ shm_unlink (shm_name);
+}
+
+static void *
+tf (void *arg)
+{
+ thread_ret = 0;
+
+ pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, 0);
+
+ if (sem_wait (&sem) != 0)
+ {
+ printf ("error: sem_wait failed: %m");
+ thread_ret = 1;
+ return NULL;
+ }
+
+ if (pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, 0) != 0)
+ {
+ printf ("error: pthread_setcancelstate failed: %m");
+ thread_ret = 1;
+ return NULL;
+ }
+
+ /* Neither sem_unlink or sem_open should act on thread cancellation. */
+ shm_unlink (shm_name);
+ on_exit (remove_shm, NULL);
+
+ int fd = shm_open (shm_name, O_CREAT, 0600);
+ if (fd == -1)
+ {
+ if (errno == ENOSYS || errno == EACCES)
+ thread_ret = 77;
+ else
+ thread_ret = 1;
+ return NULL;
+ }
+
+ if (pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, 0) != 0)
+ {
+ printf ("error: pthread_setcancelstate failed: %m");
+ thread_ret = 1;
+ return NULL;
+ }
+
+ if (close (fd) != 0)
+ {
+ printf ("error: pthread_setcancelstate failed: %m");
+ thread_ret = 1;
+ }
+
+ return NULL;
+}
+
+static int
+do_test (void)
+{
+ pthread_t td;
+
+ if (sem_init (&sem, 0, 0))
+ {
+ printf ("error: sem_init failed: %m\n");
+ return 1;
+ }
+
+ if (pthread_create (&td, NULL, tf, NULL) != 0)
+ {
+ printf ("error: pthread_create failed: %m\n");
+ return 1;
+ }
+
+ if (pthread_cancel (td) != 0)
+ {
+ printf ("error: pthread_cancel failed: %m\n");
+ return 1;
+ }
+
+ if (sem_post (&sem) != 0)
+ {
+ printf ("error: sem_post failed: %m\n");
+ return 1;
+ }
+
+ void *r;
+ if (pthread_join (td, &r) != 0)
+ {
+ printf ("error: pthread_join failed: %m\n");
+ return 1;
+ }
+
+ if (r == PTHREAD_CANCELED)
+ {
+ puts ("error: pthread_join returned PTHREAD_CANCELED");
+ return 1;
+ }
+
+ return thread_ret;
+}
+
+#define TEST_FUNCTION do_test ()
+#include <test-skeleton.c>
diff --git a/sysdeps/posix/shm_open.c b/sysdeps/posix/shm_open.c
index f296162..0182e7b 100644
--- a/sysdeps/posix/shm_open.c
+++ b/sysdeps/posix/shm_open.c
@@ -40,6 +40,11 @@ shm_open (const char *name, int oflag, mode_t mode)
# ifdef O_CLOEXEC
oflag |= O_CLOEXEC;
# endif
+
+ /* Disable asynchronous cancellation. */
+ int state;
+ pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &state);
+
int fd = open (shm_name, oflag, mode);
if (fd == -1 && __glibc_unlikely (errno == EISDIR))
/* It might be better to fold this error with EINVAL since
@@ -70,6 +75,8 @@ shm_open (const char *name, int oflag, mode_t mode)
}
# endif
+ pthread_setcancelstate (state, NULL);
+
return fd;
}
--
2.7.4