- Document that sem_wait() can fail with EINTR if it is interrupted by a

  signal.
- Fix the old ksem implementation for POSIX semaphores to not restart
  sem_wait() or sem_timedwait() if interrupted by a signal.

MFC after:	1 week

2 files changed, 11 insertions, 1 deletions

diff --git a/lib/libc/gen/sem_wait.3 b/lib/libc/gen/sem_wait.3
index 18e9586..b8303d4 100644
--- a/lib/libc/gen/sem_wait.3
+++ b/lib/libc/gen/sem_wait.3
@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 15, 2000
+.Dd April 16, 2013
 .Dt SEM_WAIT 3
 .Os
 .Sh NAME
@@ -75,6 +75,14 @@ points to an invalid semaphore.
 .El
 .Pp
 Additionally,
+.Fn sem_wait
+will fail if:
+.Bl -tag -width Er
+.Pp
+.It Bq Er EINTR
+A signal interrupted this function.
+.El
+Additionally,
 .Fn sem_trywait
 will fail if:
 .Bl -tag -width Er
diff --git a/sys/kern/uipc_sem.c b/sys/kern/uipc_sem.c
index 509f32e..0ea84fd 100644
--- a/sys/kern/uipc_sem.c
+++ b/sys/kern/uipc_sem.c
@@ -846,6 +846,8 @@ kern_sem_wait(struct thread *td, semid_t id, int tryflag,
 err:
 	mtx_unlock(&sem_lock);
 	fdrop(fp, td);
+	if (error == ERESTART)
+		error = EINTR;
 	DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
 	    (int)td->td_proc->p_pid, error));
 	return (error);