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-rw-r--r--include/linux/ptr_ring.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 37b4bb2545b3..6866df4f31b5 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -101,12 +101,18 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r)
/* Note: callers invoking this in a loop must use a compiler barrier,
* for example cpu_relax(). Callers must hold producer_lock.
+ * Callers are responsible for making sure pointer that is being queued
+ * points to a valid data.
*/
static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr)
{
if (unlikely(!r->size) || r->queue[r->producer])
return -ENOSPC;
+ /* Make sure the pointer we are storing points to a valid data. */
+ /* Pairs with smp_read_barrier_depends in __ptr_ring_consume. */
+ smp_wmb();
+
r->queue[r->producer++] = ptr;
if (unlikely(r->producer >= r->size))
r->producer = 0;
@@ -275,6 +281,9 @@ static inline void *__ptr_ring_consume(struct ptr_ring *r)
if (ptr)
__ptr_ring_discard_one(r);
+ /* Make sure anyone accessing data through the pointer is up to date. */
+ /* Pairs with smp_wmb in __ptr_ring_produce. */
+ smp_read_barrier_depends();
return ptr;
}