Merge tag 'kgdb-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt...

[linux-2.6-microblaze.git] / ipc / sem.c

diff --git a/ipc/sem.c b/ipc/sem.c
index bf534c7..971e75d 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -217,6 +217,8 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
  * this smp_load_acquire(), this is guaranteed because the smp_load_acquire()
  * is inside a spin_lock() and after a write from 0 to non-zero a
  * spin_lock()+spin_unlock() is done.
+ * To prevent the compiler/cpu temporarily writing 0 to use_global_lock,
+ * READ_ONCE()/WRITE_ONCE() is used.
  *
  * 2) queue.status: (SEM_BARRIER_2)
  * Initialization is done while holding sem_lock(), so no further barrier is
@@ -342,10 +344,10 @@ static void complexmode_enter(struct sem_array *sma)
                 * Nothing to do, just reset the
                 * counter until we return to simple mode.
                 */
-               sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS;
+               WRITE_ONCE(sma->use_global_lock, USE_GLOBAL_LOCK_HYSTERESIS);
                return;
        }
-       sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS;
+       WRITE_ONCE(sma->use_global_lock, USE_GLOBAL_LOCK_HYSTERESIS);
 
        for (i = 0; i < sma->sem_nsems; i++) {
                sem = &sma->sems[i];
@@ -371,7 +373,8 @@ static void complexmode_tryleave(struct sem_array *sma)
                /* See SEM_BARRIER_1 for purpose/pairing */
                smp_store_release(&sma->use_global_lock, 0);
        } else {
-               sma->use_global_lock--;
+               WRITE_ONCE(sma->use_global_lock,
+                               sma->use_global_lock-1);
        }
 }
 
@@ -412,7 +415,7 @@ static inline int sem_lock(struct sem_array *sma, struct sembuf *sops,
         * Initial check for use_global_lock. Just an optimization,
         * no locking, no memory barrier.
         */
-       if (!sma->use_global_lock) {
+       if (!READ_ONCE(sma->use_global_lock)) {
                /*
                 * It appears that no complex operation is around.
                 * Acquire the per-semaphore lock.
@@ -1154,7 +1157,7 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
                un->semid = -1;
                list_del_rcu(&un->list_proc);
                spin_unlock(&un->ulp->lock);
-               kfree_rcu(un, rcu);
+               kvfree_rcu(un, rcu);
        }
 
        /* Wake up all pending processes and let them fail with EIDRM. */
@@ -1937,7 +1940,8 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
        rcu_read_unlock();
 
        /* step 2: allocate new undo structure */
-       new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
+       new = kvzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems,
+                      GFP_KERNEL);
        if (!new) {
                ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
                return ERR_PTR(-ENOMEM);
@@ -1949,7 +1953,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
        if (!ipc_valid_object(&sma->sem_perm)) {
                sem_unlock(sma, -1);
                rcu_read_unlock();
-               kfree(new);
+               kvfree(new);
                un = ERR_PTR(-EIDRM);
                goto out;
        }
@@ -1960,7 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
         */
        un = lookup_undo(ulp, semid);
        if (un) {
-               kfree(new);
+               kvfree(new);
                goto success;
        }
        /* step 5: initialize & link new undo structure */
@@ -2420,7 +2424,7 @@ void exit_sem(struct task_struct *tsk)
                rcu_read_unlock();
                wake_up_q(&wake_q);
 
-               kfree_rcu(un, rcu);
+               kvfree_rcu(un, rcu);
        }
        kfree(ulp);
 }
@@ -2435,7 +2439,8 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
 
        /*
         * The proc interface isn't aware of sem_lock(), it calls
-        * ipc_lock_object() directly (in sysvipc_find_ipc).
+        * ipc_lock_object(), i.e. spin_lock(&sma->sem_perm.lock).
+        * (in sysvipc_find_ipc)
         * In order to stay compatible with sem_lock(), we must
         * enter / leave complex_mode.
         */