1 files changed, 31 insertions, 19 deletions

diff --git a/io_uring/wait.c b/io_uring/wait.c
index 0581cadf20ee..91df86ce0d18 100644
--- a/io_uring/wait.c
+++ b/io_uring/wait.c
@@ -79,12 +79,15 @@ static enum hrtimer_restart io_cqring_min_timer_wakeup(struct hrtimer *timer)
 	if (io_has_work(ctx))
 		goto out_wake;
 	/* got events since we started waiting, min timeout is done */
-	if (iowq->cq_min_tail != READ_ONCE(ctx->rings->cq.tail))
-		goto out_wake;
-	/* if we have any events and min timeout expired, we're done */
-	if (io_cqring_events(ctx))
-		goto out_wake;
+	scoped_guard(rcu) {
+		struct io_rings *rings = io_get_rings(ctx);
 
+		if (iowq->cq_min_tail != READ_ONCE(rings->cq.tail))
+			goto out_wake;
+		/* if we have any events and min timeout expired, we're done */
+		if (io_cqring_events(ctx))
+			goto out_wake;
+	}
 	/*
 	 * If using deferred task_work running and application is waiting on
 	 * more than one request, ensure we reset it now where we are switching
@@ -186,9 +189,9 @@ int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 		   struct ext_arg *ext_arg)
 {
 	struct io_wait_queue iowq;
-	struct io_rings *rings = ctx->rings;
+	struct io_rings *rings;
 	ktime_t start_time;
-	int ret;
+	int ret, nr_wait;
 
 	min_events = min_t(int, min_events, ctx->cq_entries);
 
@@ -201,15 +204,23 @@ int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 
 	if (unlikely(test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)))
 		io_cqring_do_overflow_flush(ctx);
-	if (__io_cqring_events_user(ctx) >= min_events)
+
+	rcu_read_lock();
+	rings = io_get_rings(ctx);
+	if (__io_cqring_events_user(ctx) >= min_events) {
+		rcu_read_unlock();
 		return 0;
+	}
 
 	init_waitqueue_func_entry(&iowq.wq, io_wake_function);
 	iowq.wq.private = current;
 	INIT_LIST_HEAD(&iowq.wq.entry);
 	iowq.ctx = ctx;
-	iowq.cq_tail = READ_ONCE(ctx->rings->cq.head) + min_events;
-	iowq.cq_min_tail = READ_ONCE(ctx->rings->cq.tail);
+	iowq.cq_tail = READ_ONCE(rings->cq.head) + min_events;
+	iowq.cq_min_tail = READ_ONCE(rings->cq.tail);
+	nr_wait = (int) iowq.cq_tail - READ_ONCE(rings->cq.tail);
+	rcu_read_unlock();
+	rings = NULL;
 	iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
 	iowq.hit_timeout = 0;
 	iowq.min_timeout = ext_arg->min_time;
@@ -240,14 +251,6 @@ int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 	trace_io_uring_cqring_wait(ctx, min_events);
 	do {
 		unsigned long check_cq;
-		int nr_wait;
-
-		/* if min timeout has been hit, don't reset wait count */
-		if (!iowq.hit_timeout)
-			nr_wait = (int) iowq.cq_tail -
-					READ_ONCE(ctx->rings->cq.tail);
-		else
-			nr_wait = 1;
 
 		if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
 			atomic_set(&ctx->cq_wait_nr, nr_wait);
@@ -298,11 +301,20 @@ int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, u32 flags,
 			break;
 		}
 		cond_resched();
+
+		/* if min timeout has been hit, don't reset wait count */
+		if (!iowq.hit_timeout)
+			scoped_guard(rcu)
+				nr_wait = (int) iowq.cq_tail -
+						READ_ONCE(io_get_rings(ctx)->cq.tail);
+		else
+			nr_wait = 1;
 	} while (1);
 
 	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
 		finish_wait(&ctx->cq_wait, &iowq.wq);
 	restore_saved_sigmask_unless(ret == -EINTR);
 
-	return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
+	guard(rcu)();
+	return READ_ONCE(io_get_rings(ctx)->cq.head) == READ_ONCE(io_get_rings(ctx)->cq.tail) ? ret : 0;
 }