io_uring: remove wait loop spurious wakeups

Any changes interesting to tasks waiting in io_cqring_wait() are
commited with io_cqring_ev_posted(). However, io_ring_drop_ctx_refs()
also tries to do that but with no reason, that means spurious wakeups
every io_free_req() and io_uring_enter().

Just use percpu_ref_put() instead.

Signed-off-by: Pavel Begunkov <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 ab8c4e5..ceb3497 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -591,14 +591,6 @@ static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
        io_cqring_ev_posted(ctx);
 }
 
-static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
-{
-       percpu_ref_put_many(&ctx->refs, refs);
-
-       if (waitqueue_active(&ctx->wait))
-               wake_up(&ctx->wait);
-}
-
 static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
                                   struct io_submit_state *state)
 {
@@ -646,7 +638,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
        req->result = 0;
        return req;
 out:
-       io_ring_drop_ctx_refs(ctx, 1);
+       percpu_ref_put(&ctx->refs);
        return NULL;
 }
 
@@ -654,7 +646,7 @@ static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
 {
        if (*nr) {
                kmem_cache_free_bulk(req_cachep, *nr, reqs);
-               io_ring_drop_ctx_refs(ctx, *nr);
+               percpu_ref_put_many(&ctx->refs, *nr);
                *nr = 0;
        }
 }
@@ -663,7 +655,7 @@ static void __io_free_req(struct io_kiocb *req)
 {
        if (req->file && !(req->flags & REQ_F_FIXED_FILE))
                fput(req->file);
-       io_ring_drop_ctx_refs(req->ctx, 1);
+       percpu_ref_put(&req->ctx->refs);
        kmem_cache_free(req_cachep, req);
 }
 
@@ -3584,7 +3576,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
                }
        }
 
-       io_ring_drop_ctx_refs(ctx, 1);
+       percpu_ref_put(&ctx->refs);
 out_fput:
        fdput(f);
        return submitted ? submitted : ret;