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Commit 6805b32e authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

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: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b84477d3

fs/io_uring.c

+4 −12
Original line number Diff line number Diff line
@@ -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;