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am 2d988187: am 11829be3: Merge "Add test about pthread_mutex_t owner tid limit."

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* commit '2d988187712f52773b89421d139b266c8b58f769':
  Add test about pthread_mutex_t owner tid limit.
This commit is contained in:
Yabin Cui 2015-02-03 22:40:46 +00:00 committed by Android Git Automerger
commit 70ad54d8c0
2 changed files with 15 additions and 24 deletions
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27
libc/bionic/pthread_mutex.cpp
View file

@ -150,30 +150,9 @@
/* Mutex owner field:
*
* This is only used for recursive and errorcheck mutexes. It holds the
* tid of the owning thread. Note that this works because the Linux
* kernel _only_ uses 16-bit values for tids.
*
* More specifically, it will wrap to 10000 when it reaches over 32768 for
* application processes. You can check this by running the following inside
* an adb shell session:
*
OLDPID=$$;
while true; do
NEWPID=$(sh -c 'echo $$')
if [ "$NEWPID" -gt 32768 ]; then
echo "AARGH: new PID $NEWPID is too high!"
exit 1
fi
if [ "$NEWPID" -lt "$OLDPID" ]; then
echo "****** Wrapping from PID $OLDPID to $NEWPID. *******"
else
echo -n "$NEWPID!"
fi
OLDPID=$NEWPID
done
* Note that you can run the same example on a desktop Linux system,
* the wrapping will also happen at 32768, but will go back to 300 instead.
* tid of the owning thread. We use 16 bits to represent tid here,
* so the highest tid is 65535. There is a test to check /proc/sys/kernel/pid_max
* to make sure it will not exceed our limit.
*/
#define MUTEX_OWNER_SHIFT 16
#define MUTEX_OWNER_LEN 16

12
tests/pthread_test.cpp
View file

@ -27,6 +27,7 @@
#include <malloc.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <time.h>
@ -1092,3 +1093,14 @@ TEST(pthread, pthread_mutex_lock_RECURSIVE) {
ASSERT_EQ(EPERM, pthread_mutex_unlock(&lock));
ASSERT_EQ(0, pthread_mutex_destroy(&lock));
}
TEST(pthread, pthread_mutex_owner_tid_limit) {
FILE* fp = fopen("/proc/sys/kernel/pid_max", "r");
ASSERT_TRUE(fp != NULL);
long pid_max;
ASSERT_EQ(1, fscanf(fp, "%ld", &pid_max));
fclose(fp);
// Current pthread_mutex uses 16 bits to represent owner tid.
// Change the implementation if we need to support higher value than 65535.
ASSERT_LE(pid_max, 65536);
}