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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2020-11-26 10:54:04 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2020-11-27 09:59:13 -0300
commitaa69f19a937b679816ef10e8620ea1141bb1734b (patch)
treefda886e3c6899912d8ebb5e65ace4710075bbc0f /nptl/pthread_mutex_timedlock.c
parent71eeae0325a95f5e5d7ec4a27a6a6c357e0c8ef4 (diff)
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nptl: Add EOVERFLOW checks for futex calls
Some futex-internal calls require additional check for EOVERFLOW (as
indicated by [1] [2] [3]).  For both mutex and rwlock code, EOVERFLOW is
handle as ETIMEDOUT; since it indicate to the caller that the blocking
operation could not be issued.

For mutex it avoids a possible issue where PTHREAD_MUTEX_ROBUST_* might
assume EOVERFLOW indicate futex has succeed, and for PTHREAD_MUTEX_PP_*
it avoid a potential busy infinite loop.  For rwlock and semaphores, it
also avoids potential busy infinite loops.

Checked on x86_64-linux-gnu and i686-linux-gnu, although EOVERFLOW
won't be possible with current usage (since all timeouts on 32-bit
architectures with 32-bit time_t support will be in the range of
32-bit time_t).

[1] https://sourceware.org/pipermail/libc-alpha/2020-November/120079.html
[2] https://sourceware.org/pipermail/libc-alpha/2020-November/120080.html
[3] https://sourceware.org/pipermail/libc-alpha/2020-November/120127.html
Diffstat (limited to 'nptl/pthread_mutex_timedlock.c')
-rw-r--r--nptl/pthread_mutex_timedlock.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
index 74adffe790..6c72a36b2b 100644
--- a/nptl/pthread_mutex_timedlock.c
+++ b/nptl/pthread_mutex_timedlock.c
@@ -270,7 +270,7 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
 	      oldval, clockid, abstime,
 	      PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 	  /* The futex call timed out.  */
-	  if (err == ETIMEDOUT)
+	  if (err == ETIMEDOUT || err == EOVERFLOW)
 	    return err;
 	  /* Reload current lock value.  */
 	  oldval = mutex->__data.__lock;
@@ -550,8 +550,8 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
 		    int e = __futex_abstimed_wait64 (
 		      (unsigned int *) &mutex->__data.__lock, ceilval | 2,
 		      clockid, abstime, PTHREAD_MUTEX_PSHARED (mutex));
-		    if (e == ETIMEDOUT)
-		      return ETIMEDOUT;
+		    if (e == ETIMEDOUT || e == EOVERFLOW)
+		      return e;
 		  }
 	      }
 	    while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,