io_uring: merge CQ and poll waitqueues

->cq_wait and ->poll_wait and waken up in the same manner, use a single
waitqueue for both of them. CQ waiters are queued exclusively, so wake
up should first go over all pollers and that's what we need.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/00fe603e50000365774cf8435ef5fe03f049c1c9.1633373302.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index af2cbe6..c9e6f4b 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -394,7 +394,6 @@ struct io_ring_ctx {
                unsigned                cached_cq_tail;
                unsigned                cq_entries;
                struct eventfd_ctx      *cq_ev_fd;
-               struct wait_queue_head  poll_wait;
                struct wait_queue_head  cq_wait;
                unsigned                cq_extra;
                atomic_t                cq_timeouts;
@@ -1300,7 +1299,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
        ctx->flags = p->flags;
        init_waitqueue_head(&ctx->sqo_sq_wait);
        INIT_LIST_HEAD(&ctx->sqd_list);
-       init_waitqueue_head(&ctx->poll_wait);
        INIT_LIST_HEAD(&ctx->cq_overflow_list);
        init_completion(&ctx->ref_comp);
        xa_init_flags(&ctx->io_buffers, XA_FLAGS_ALLOC1);
@@ -1621,8 +1619,6 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
                wake_up_all(&ctx->cq_wait);
        if (io_should_trigger_evfd(ctx))
                eventfd_signal(ctx->cq_ev_fd, 1);
-       if (waitqueue_active(&ctx->poll_wait))
-               wake_up_interruptible(&ctx->poll_wait);
 }
 
 static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
@@ -1636,8 +1632,6 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
        }
        if (io_should_trigger_evfd(ctx))
                eventfd_signal(ctx->cq_ev_fd, 1);
-       if (waitqueue_active(&ctx->poll_wait))
-               wake_up_interruptible(&ctx->poll_wait);
 }
 
 /* Returns true if there are no backlogged entries after the flush */
@@ -9253,7 +9247,7 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
        struct io_ring_ctx *ctx = file->private_data;
        __poll_t mask = 0;
 
-       poll_wait(file, &ctx->poll_wait, wait);
+       poll_wait(file, &ctx->cq_wait, wait);
        /*
         * synchronizes with barrier from wq_has_sleeper call in
         * io_commit_cqring