drm/radeon: forever loop on error in radeon_do_test_moves()

[karo-tx-linux.git] / ipc / sem.c

diff --git a/ipc/sem.c b/ipc/sem.c
index 4a92c0447ad66d4a351a3988dbda69df641573e1..8c4f59b0204a2821811a4b28fd48e0ce6163d987 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -257,12 +257,20 @@ static void sem_rcu_free(struct rcu_head *head)
  * Caller must own sem_perm.lock.
  * New simple ops cannot start, because simple ops first check
  * that sem_perm.lock is free.
+ * that a) sem_perm.lock is free and b) complex_count is 0.
  */
 static void sem_wait_array(struct sem_array *sma)
 {
        int i;
        struct sem *sem;
 
+       if (sma->complex_count)  {
+               /* The thread that increased sma->complex_count waited on
+                * all sem->lock locks. Thus we don't need to wait again.
+                */
+               return;
+       }
+
        for (i = 0; i < sma->sem_nsems; i++) {
                sem = sma->sem_base + i;
                spin_unlock_wait(&sem->lock);
@@ -909,6 +917,24 @@ again:
        return semop_completed;
 }
 
+/**
+ * set_semotime(sma, sops) - set sem_otime
+ * @sma: semaphore array
+ * @sops: operations that modified the array, may be NULL
+ *
+ * sem_otime is replicated to avoid cache line trashing.
+ * This function sets one instance to the current time.
+ */
+static void set_semotime(struct sem_array *sma, struct sembuf *sops)
+{
+       if (sops == NULL) {
+               sma->sem_base[0].sem_otime = get_seconds();
+       } else {
+               sma->sem_base[sops[0].sem_num].sem_otime =
+                                                       get_seconds();
+       }
+}
+
 /**
  * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue
  * @sma: semaphore array
@@ -959,17 +985,10 @@ static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsop
                        }
                }
        }
-       if (otime) {
-               if (sops == NULL) {
-                       sma->sem_base[0].sem_otime = get_seconds();
-               } else {
-                       sma->sem_base[sops[0].sem_num].sem_otime =
-                                                               get_seconds();
-               }
-       }
+       if (otime)
+               set_semotime(sma, sops);
 }
 
-
 /* The following counts are associated to each semaphore:
  *   semncnt        number of tasks waiting on semval being nonzero
  *   semzcnt        number of tasks waiting on semval being zero
@@ -1831,12 +1850,17 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
 
        error = perform_atomic_semop(sma, sops, nsops, un,
                                        task_tgid_vnr(current));
-       if (error <= 0) {
-               if (alter && error == 0)
+       if (error == 0) {
+               /* If the operation was successful, then do
+                * the required updates.
+                */
+               if (alter)
                        do_smart_update(sma, sops, nsops, 1, &tasks);
-
-               goto out_unlock_free;
+               else
+                       set_semotime(sma, sops);
        }
+       if (error <= 0)
+               goto out_unlock_free;
 
        /* We need to sleep on this operation, so we put the current
         * task into the pending queue and go to sleep.
@@ -2095,6 +2119,14 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
        struct sem_array *sma = it;
        time_t sem_otime;
 
+       /*
+        * The proc interface isn't aware of sem_lock(), it calls
+        * ipc_lock_object() directly (in sysvipc_find_ipc).
+        * In order to stay compatible with sem_lock(), we must wait until
+        * all simple semop() calls have left their critical regions.
+        */
+       sem_wait_array(sma);
+
        sem_otime = get_semotime(sma);
 
        return seq_printf(s,