Add test about pthread_mutex_t owner tid limit.
Bug: 19216648
Change-Id: I7b12955bdcad31c13bf8ec2740ff88ba15223ec0
diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index a0628b0..83d6b54 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -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