Merge tag 'for-5.4/io_uring-2019-09-27' of git://git.kernel.dk/linux-block

[sfrench/cifs-2.6.git] / fs / io_uring.c

diff --git a/fs/io_uring.c b/fs/io_uring.c
index dd094b387cabeed7c0ed413f9128d15e5c8dd84b..aa8ac557493cb5e20f1ac78a87bb6b8e6e6f6fe8 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2768,6 +2768,38 @@ out:
        return submit;
 }
 
+struct io_wait_queue {
+       struct wait_queue_entry wq;
+       struct io_ring_ctx *ctx;
+       unsigned to_wait;
+       unsigned nr_timeouts;
+};
+
+static inline bool io_should_wake(struct io_wait_queue *iowq)
+{
+       struct io_ring_ctx *ctx = iowq->ctx;
+
+       /*
+        * Wake up if we have enough events, or if a timeout occured since we
+        * started waiting. For timeouts, we always want to return to userspace,
+        * regardless of event count.
+        */
+       return io_cqring_events(ctx->rings) >= iowq->to_wait ||
+                       atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
+}
+
+static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
+                           int wake_flags, void *key)
+{
+       struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue,
+                                                       wq);
+
+       if (!io_should_wake(iowq))
+               return -1;
+
+       return autoremove_wake_function(curr, mode, wake_flags, key);
+}
+
 /*
  * Wait until events become available, if we don't already have some. The
  * application must reap them itself, as they reside on the shared cq ring.
@@ -2775,8 +2807,16 @@ out:
 static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                          const sigset_t __user *sig, size_t sigsz)
 {
+       struct io_wait_queue iowq = {
+               .wq = {
+                       .private        = current,
+                       .func           = io_wake_function,
+                       .entry          = LIST_HEAD_INIT(iowq.wq.entry),
+               },
+               .ctx            = ctx,
+               .to_wait        = min_events,
+       };
        struct io_rings *rings = ctx->rings;
-       unsigned nr_timeouts;
        int ret;
 
        if (io_cqring_events(rings) >= min_events)
@@ -2795,15 +2835,21 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
                        return ret;
        }
 
-       nr_timeouts = atomic_read(&ctx->cq_timeouts);
-       /*
-        * Return if we have enough events, or if a timeout occured since
-        * we started waiting. For timeouts, we always want to return to
-        * userspace.
-        */
-       ret = wait_event_interruptible(ctx->wait,
-                               io_cqring_events(rings) >= min_events ||
-                               atomic_read(&ctx->cq_timeouts) != nr_timeouts);
+       ret = 0;
+       iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
+       do {
+               prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
+                                               TASK_INTERRUPTIBLE);
+               if (io_should_wake(&iowq))
+                       break;
+               schedule();
+               if (signal_pending(current)) {
+                       ret = -ERESTARTSYS;
+                       break;
+               }
+       } while (1);
+       finish_wait(&ctx->wait, &iowq.wq);
+
        restore_saved_sigmask_unless(ret == -ERESTARTSYS);
        if (ret == -ERESTARTSYS)
                ret = -EINTR;
@@ -3455,7 +3501,7 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
        if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
            ctx->rings->sq_ring_entries)
                mask |= EPOLLOUT | EPOLLWRNORM;
-       if (READ_ONCE(ctx->rings->sq.head) != ctx->cached_cq_tail)
+       if (READ_ONCE(ctx->rings->cq.head) != ctx->cached_cq_tail)
                mask |= EPOLLIN | EPOLLRDNORM;
 
        return mask;