[LTP] [PATCH] open_posix: condvar/schedule: remove signal handlers
Jan Stancek
jstancek@redhat.com
Tue Feb 23 13:43:27 CET 2016
POSIX states:
"It is not safe to use the pthread_cond_signal() function in a signal
handler that is invoked asynchronously. Even if it were safe, there
would still be a race between the test of the Boolean pthread_cond_wait()
that could not be efficiently eliminated."
Further, this test could hang on single CPU, if signal gets delivered
to main thread, because there is low prio thread busy looping with
higher priority than main.
This patch removes signal handlers and instead uses main to
signal/unlock condition/barrier/mutex that high prio thread is
blocked on.
High and low prio threads are set to run on same CPU to check that
high prio thread really preempted low prio thread regarless of number
of CPUs on system. Main thread's priority is at least the same as
low prio thread, therefore it should eventually run even if there
is only single CPU on system.
Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
.../threads/condvar/pthread_cond_wait_1.c | 41 ++++++++-------------
.../threads/condvar/pthread_cond_wait_2.c | 41 ++++++++-------------
.../functional/threads/schedule/1-1.c | 43 ++++++++--------------
.../functional/threads/schedule/1-2.c | 32 +++++-----------
4 files changed, 57 insertions(+), 100 deletions(-)
diff --git a/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_1.c b/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_1.c
index a674efc406ef..b2ad5463ff13 100644
--- a/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_1.c
+++ b/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_1.c
@@ -13,14 +13,15 @@
* 1. Create a condition variable
* 2. Create a high priority thread and make it wait on the cond
* 3. Create a low priority thread and let it busy-loop
- * 4. Signal the cond in a signal handler and check that high
- * priority thread got woken up
+ * 4. Both low and high prio threads run on same CPU
+ * 5. Signal the cond from main and check that high priority thread
+ * got woken up and preempted low priority thread
*/
+#include "affinity.h"
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
-#include <signal.h>
#include <unistd.h>
#include <time.h>
#include "posixtest.h"
@@ -42,12 +43,6 @@ pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
static volatile int woken_up;
static volatile int low_done;
-void signal_handler(int sig)
-{
- (void) sig;
- SAFE_PFUNC(pthread_cond_signal(&cond));
-}
-
float timediff(struct timespec t2, struct timespec t1)
{
float diff = t2.tv_sec - t1.tv_sec;
@@ -61,6 +56,7 @@ void *hi_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if ((policy != POLICY) || (param.sched_priority != HIGH_PRIORITY)) {
@@ -68,15 +64,8 @@ void *hi_prio_thread(void *tmp)
exit(PTS_UNRESOLVED);
}
- if (signal(SIGALRM, signal_handler) != 0) {
- perror(ERROR_PREFIX "signal:");
- exit(PTS_UNRESOLVED);
- }
-
SAFE_PFUNC(pthread_mutex_lock(&mutex));
- alarm(2);
-
/* Block, to be woken up by the signal handler */
SAFE_PFUNC(pthread_cond_wait(&cond, &mutex));
@@ -97,6 +86,7 @@ void *low_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if ((policy != POLICY) || (param.sched_priority != LOW_PRIORITY)) {
@@ -117,7 +107,7 @@ void *low_prio_thread(void *tmp)
int main()
{
pthread_t high_id, low_id;
- pthread_attr_t high_attr, low_attr;
+ pthread_attr_t high_attr;
struct sched_param param;
/* Create the higher priority thread */
@@ -128,22 +118,23 @@ int main()
SAFE_PFUNC(pthread_attr_setschedparam(&high_attr, ¶m));
SAFE_PFUNC(pthread_create(&high_id, &high_attr, hi_prio_thread, NULL));
- /* Create the low priority thread */
- SAFE_PFUNC(pthread_attr_init(&low_attr));
- SAFE_PFUNC(pthread_attr_setinheritsched(&low_attr, PTHREAD_EXPLICIT_SCHED));
- SAFE_PFUNC(pthread_attr_setschedpolicy(&low_attr, POLICY));
+ /* run main with same priority as low prio thread */
param.sched_priority = LOW_PRIORITY;
- SAFE_PFUNC(pthread_attr_setschedparam(&low_attr, ¶m));
- SAFE_PFUNC(pthread_create(&low_id, &low_attr, low_prio_thread, NULL));
+ SAFE_PFUNC(pthread_setschedparam(pthread_self(), POLICY, ¶m));
+
+ /* Create the low priority thread (inherits sched policy from main) */
+ SAFE_PFUNC(pthread_create(&low_id, NULL, low_prio_thread, NULL));
+
+ sleep(1);
+ SAFE_PFUNC(pthread_cond_signal(&cond));
/* Wait for the threads to exit */
- SAFE_PFUNC(pthread_join(high_id, NULL));
SAFE_PFUNC(pthread_join(low_id, NULL));
-
if (!woken_up) {
printf("Test FAILED: high priority was not woken up\n");
exit(PTS_FAIL);
}
+ SAFE_PFUNC(pthread_join(high_id, NULL));
printf("Test PASSED\n");
exit(PTS_PASS);
diff --git a/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_2.c b/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_2.c
index 398b8db5448e..a7826cd04dfd 100644
--- a/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_2.c
+++ b/testcases/open_posix_testsuite/functional/threads/condvar/pthread_cond_wait_2.c
@@ -13,14 +13,15 @@
* 1. Create a condition variable
* 2. Create a high priority thread and make it wait on the cond
* 3. Create a low priority thread and let it busy-loop
- * 4. Broadcast the cond in a signal handler and check that high
- * priority thread got woken up
+ * 4. Both low and high prio threads run on same CPU
+ * 5. Signal the cond from main and check that high priority thread
+ * got woken up and preempted low priority thread
*/
+#include "affinity.h"
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
-#include <signal.h>
#include <unistd.h>
#include <time.h>
#include "posixtest.h"
@@ -42,12 +43,6 @@ pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
static volatile int woken_up;
static volatile int low_done;
-void signal_handler(int sig)
-{
- (void) sig;
- SAFE_PFUNC(pthread_cond_broadcast(&cond));
-}
-
float timediff(struct timespec t2, struct timespec t1)
{
float diff = t2.tv_sec - t1.tv_sec;
@@ -61,6 +56,7 @@ void *hi_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if ((policy != POLICY) || (param.sched_priority != HIGH_PRIORITY)) {
@@ -68,15 +64,8 @@ void *hi_prio_thread(void *tmp)
exit(PTS_UNRESOLVED);
}
- if (signal(SIGALRM, signal_handler) != 0) {
- perror(ERROR_PREFIX "signal:");
- exit(PTS_UNRESOLVED);
- }
-
SAFE_PFUNC(pthread_mutex_lock(&mutex));
- alarm(2);
-
/* Block, to be woken up by the signal handler */
SAFE_PFUNC(pthread_cond_wait(&cond, &mutex));
@@ -97,6 +86,7 @@ void *low_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if ((policy != POLICY) || (param.sched_priority != LOW_PRIORITY)) {
@@ -117,7 +107,7 @@ void *low_prio_thread(void *tmp)
int main()
{
pthread_t high_id, low_id;
- pthread_attr_t high_attr, low_attr;
+ pthread_attr_t high_attr;
struct sched_param param;
/* Create the higher priority thread */
@@ -128,22 +118,23 @@ int main()
SAFE_PFUNC(pthread_attr_setschedparam(&high_attr, ¶m));
SAFE_PFUNC(pthread_create(&high_id, &high_attr, hi_prio_thread, NULL));
- /* Create the low priority thread */
- SAFE_PFUNC(pthread_attr_init(&low_attr));
- SAFE_PFUNC(pthread_attr_setinheritsched(&low_attr, PTHREAD_EXPLICIT_SCHED));
- SAFE_PFUNC(pthread_attr_setschedpolicy(&low_attr, POLICY));
+ /* run main with same priority as low prio thread */
param.sched_priority = LOW_PRIORITY;
- SAFE_PFUNC(pthread_attr_setschedparam(&low_attr, ¶m));
- SAFE_PFUNC(pthread_create(&low_id, &low_attr, low_prio_thread, NULL));
+ SAFE_PFUNC(pthread_setschedparam(pthread_self(), POLICY, ¶m));
+
+ /* Create the low priority thread (inherits sched policy from main) */
+ SAFE_PFUNC(pthread_create(&low_id, NULL, low_prio_thread, NULL));
+
+ sleep(1);
+ SAFE_PFUNC(pthread_cond_broadcast(&cond));
/* Wait for the threads to exit */
- SAFE_PFUNC(pthread_join(high_id, NULL));
SAFE_PFUNC(pthread_join(low_id, NULL));
-
if (!woken_up) {
printf("Test FAILED: high priority was not woken up\n");
exit(PTS_FAIL);
}
+ SAFE_PFUNC(pthread_join(high_id, NULL));
printf("Test PASSED\n");
exit(PTS_PASS);
diff --git a/testcases/open_posix_testsuite/functional/threads/schedule/1-1.c b/testcases/open_posix_testsuite/functional/threads/schedule/1-1.c
index c65e127bdf5b..d92680154138 100644
--- a/testcases/open_posix_testsuite/functional/threads/schedule/1-1.c
+++ b/testcases/open_posix_testsuite/functional/threads/schedule/1-1.c
@@ -13,16 +13,17 @@
* 1. Create a barrier object
* 2. Create a high priority thread and make it wait on the barrier
* 3. Create a low priority thread and let it busy-loop
- * 4. Setup a signal handler for ALRM
- * 5. Call the final barrier_wait in the signal handler
+ * 4. Both low and high prio threads run on same CPU
+ * 5. Call the final barrier_wait from main
* 6. Check that the higher priority thread got woken up
+ * and preempted low priority thread
*/
#define _XOPEN_SOURCE 600
+#include "affinity.h"
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
-#include <signal.h>
#include <unistd.h>
#include <sys/time.h>
#include "posixtest.h"
@@ -57,19 +58,13 @@ int my_pthread_barrier_wait(pthread_barrier_t *p)
return rc;
}
-void signal_handler(int sig)
-{
- (void) sig;
- SAFE_PFUNC(my_pthread_barrier_wait(&barrier));
-}
-
void *hi_prio_thread(void *tmp)
{
struct sched_param param;
int policy;
- void *previous_signal;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if (policy != SCHED_RR || param.sched_priority != HIGH_PRIORITY) {
@@ -77,14 +72,6 @@ void *hi_prio_thread(void *tmp)
exit(PTS_UNRESOLVED);
}
- previous_signal = signal(SIGALRM, signal_handler);
- if (previous_signal == SIG_ERR) {
- perror(ERROR_PREFIX "signal");
- exit(PTS_UNRESOLVED);
- }
-
- alarm(2);
-
SAFE_PFUNC(my_pthread_barrier_wait(&barrier));
/* This variable is unprotected because the scheduling removes
@@ -103,6 +90,7 @@ void *low_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if (policy != SCHED_RR || param.sched_priority != LOW_PRIORITY) {
@@ -124,7 +112,7 @@ void *low_prio_thread(void *tmp)
int main()
{
pthread_t high_id, low_id;
- pthread_attr_t low_attr, high_attr;
+ pthread_attr_t high_attr;
struct sched_param param;
SAFE_PFUNC(pthread_barrier_init(&barrier, NULL, 2));
@@ -137,22 +125,23 @@ int main()
SAFE_PFUNC(pthread_attr_setschedparam(&high_attr, ¶m));
SAFE_PFUNC(pthread_create(&high_id, &high_attr, hi_prio_thread, NULL));
- /* Create the low priority thread */
- SAFE_PFUNC(pthread_attr_init(&low_attr));
- SAFE_PFUNC(pthread_attr_setinheritsched(&low_attr, PTHREAD_EXPLICIT_SCHED));
- SAFE_PFUNC(pthread_attr_setschedpolicy(&low_attr, SCHED_RR));
+ /* run main with same priority as low prio thread */
param.sched_priority = LOW_PRIORITY;
- SAFE_PFUNC(pthread_attr_setschedparam(&low_attr, ¶m));
- SAFE_PFUNC(pthread_create(&low_id, &low_attr, low_prio_thread, NULL));
+ SAFE_PFUNC(pthread_setschedparam(pthread_self(), SCHED_RR, ¶m));
+
+ /* Create the low priority thread (inherits sched policy from main) */
+ SAFE_PFUNC(pthread_create(&low_id, NULL, low_prio_thread, NULL));
+
+ sleep(1);
+ SAFE_PFUNC(my_pthread_barrier_wait(&barrier));
/* Wait for the threads to exit */
- SAFE_PFUNC(pthread_join(high_id, NULL));
SAFE_PFUNC(pthread_join(low_id, NULL));
-
if (!woken_up) {
printf("High priority was not woken up. Test FAILED\n");
exit(PTS_FAIL);
}
+ SAFE_PFUNC(pthread_join(high_id, NULL));
printf("Test PASSED\n");
exit(PTS_PASS);
diff --git a/testcases/open_posix_testsuite/functional/threads/schedule/1-2.c b/testcases/open_posix_testsuite/functional/threads/schedule/1-2.c
index c85460e7cf89..92e3ef153d9d 100644
--- a/testcases/open_posix_testsuite/functional/threads/schedule/1-2.c
+++ b/testcases/open_posix_testsuite/functional/threads/schedule/1-2.c
@@ -13,14 +13,15 @@
* 1. Create a mutex and lock
* 2. Create a high priority thread and make it wait on the mutex
* 3. Create a low priority thread and let it busy-loop
- * 4. Unlock the mutex and make sure that the higher priority thread
- * got woken up
+ * 4. Both low and high prio threads run on same CPU
+ * 5. Unlock the mutex and make sure that the higher priority thread
+ * got woken up and preempted low priority thread
*/
+#include "affinity.h"
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
-#include <signal.h>
#include <unistd.h>
#include <sys/time.h>
#include "posixtest.h"
@@ -36,8 +37,6 @@
#define RUNTIME 5
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-pthread_mutex_t cond_mutex = PTHREAD_MUTEX_INITIALIZER;
-pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
static volatile int woken_up;
static volatile int low_done;
@@ -49,18 +48,13 @@ float timediff(struct timespec t2, struct timespec t1)
return diff;
}
-void signal_handler(int sig)
-{
- (void) sig;
- SAFE_PFUNC(pthread_cond_signal(&cond));
-}
-
void *hi_prio_thread(void *tmp)
{
struct sched_param param;
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if (policy != SCHED_RR) {
@@ -91,6 +85,7 @@ void *low_prio_thread(void *tmp)
int policy;
(void) tmp;
+ set_affinity_single();
SAFE_PFUNC(pthread_getschedparam(pthread_self(), &policy, ¶m));
if (policy != SCHED_RR) {
@@ -149,28 +144,19 @@ int main()
SAFE_PFUNC(pthread_attr_setschedparam(&low_attr, ¶m));
SAFE_PFUNC(pthread_create(&low_id, &low_attr, low_prio_thread, NULL));
- /* setup a signal handler which will wakeup main later */
- if (signal(SIGALRM, signal_handler) == SIG_ERR) {
- perror(ERROR_PREFIX "signal");
- exit(PTS_UNRESOLVED);
- }
-
- SAFE_PFUNC(pthread_mutex_lock(&cond_mutex));
- alarm(2);
- SAFE_PFUNC(pthread_cond_wait(&cond, &cond_mutex));
- SAFE_PFUNC(pthread_mutex_unlock(&cond_mutex));
+ sleep(1);
/* Wake the other high priority thread up */
SAFE_PFUNC(pthread_mutex_unlock(&mutex));
/* Wait for the threads to exit */
- SAFE_PFUNC(pthread_join(high_id, NULL));
SAFE_PFUNC(pthread_join(low_id, NULL));
-
if (!woken_up) {
printf("High priority was not woken up. Test FAILED.\n");
exit(PTS_FAIL);
}
+ SAFE_PFUNC(pthread_join(high_id, NULL));
+
printf("Test PASSED\n");
exit(PTS_PASS);
}
--
1.8.3.1
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