Commit 6971253f authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: revise completion_lock locking 



io_kill_timeouts() doesn't post any events but queues everything to
task_work. Locking there is needed for protecting linked requests
traversing, we should grab completion_lock directly instead of using
io_cq_[un]lock helpers. Same goes for __io_req_find_next_prep().

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/88e75d481a65dc295cb59722bb1cf76402d1c06b.1670002973.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ea011ee1

io_uring/io_uring.c

+14 −2
Original line number Diff line number Diff line
@@ -597,6 +597,18 @@ static inline void __io_cq_unlock(struct io_ring_ctx *ctx) 
		spin_unlock(&ctx->completion_lock);

}



static inline void io_cq_lock(struct io_ring_ctx *ctx)

	__acquires(ctx->completion_lock)

{

	spin_lock(&ctx->completion_lock);

}



static inline void io_cq_unlock(struct io_ring_ctx *ctx)

	__releases(ctx->completion_lock)

{

	spin_unlock(&ctx->completion_lock);

}



/* keep it inlined for io_submit_flush_completions() */

static inline void __io_cq_unlock_post(struct io_ring_ctx *ctx)

	__releases(ctx->completion_lock)
@@ -1074,9 +1086,9 @@ static void __io_req_find_next_prep(struct io_kiocb *req) 
{

	struct io_ring_ctx *ctx = req->ctx;



	io_cq_lock(ctx);

	spin_lock(&ctx->completion_lock);

	io_disarm_next(req);

	io_cq_unlock_post(ctx);

	spin_unlock(&ctx->completion_lock);

}



static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)

io_uring/io_uring.h

+0 −11
Original line number Diff line number Diff line
@@ -87,17 +87,6 @@ static inline void io_req_task_work_add(struct io_kiocb *req) 
#define io_for_each_link(pos, head) \

	for (pos = (head); pos; pos = pos->link)



static inline void io_cq_lock(struct io_ring_ctx *ctx)

	__acquires(ctx->completion_lock)

{

	spin_lock(&ctx->completion_lock);

}



static inline void io_cq_unlock(struct io_ring_ctx *ctx)

{

	spin_unlock(&ctx->completion_lock);

}



void io_cq_unlock_post(struct io_ring_ctx *ctx);



static inline struct io_uring_cqe *io_get_cqe_overflow(struct io_ring_ctx *ctx,

io_uring/timeout.c

+6 −2
Original line number Diff line number Diff line
@@ -624,7 +624,11 @@ __cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk, 
	struct io_timeout *timeout, *tmp;

	int canceled = 0;



	io_cq_lock(ctx);

	/*

	 * completion_lock is needed for io_match_task(). Take it before

	 * timeout_lockfirst to keep locking ordering.

	 */

	spin_lock(&ctx->completion_lock);

	spin_lock_irq(&ctx->timeout_lock);

	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {

		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
@@ -634,6 +638,6 @@ __cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk, 
			canceled++;

	}

	spin_unlock_irq(&ctx->timeout_lock);

	io_cq_unlock_post(ctx);

	spin_unlock(&ctx->completion_lock);

	return canceled != 0;

}