From c98de08c990e190fc7cc3aaf8079b4a0674c6425 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sun, 15 Nov 2020 12:56:32 +0000 Subject: [PATCH] io_uring: replace inflight_wait with tctx->wait As tasks now cancel only theirs requests, and inflight_wait is awaited only in io_uring_cancel_files(), which should be called with ->in_idle set, instead of keeping a separate inflight_wait use tctx->wait. That will add some spurious wakeups but actually is safer from point of not hanging the task. e.g. task1 | IRQ | *start* io_complete_rw_common(link) | link: req1 -> req2 -> req3(with files) *cancel_files() | io_wq_cancel(), etc. | | put_req(link), adds to io-wq req2 schedule() | So, task1 will never try to cancel req2 or req3. If req2 is long-standing (e.g. read(empty_pipe)), this may hang. Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- fs/io_uring.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 33c4487..c42321e 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -287,7 +287,6 @@ struct io_ring_ctx { struct list_head timeout_list; struct list_head cq_overflow_list; - wait_queue_head_t inflight_wait; struct io_uring_sqe *sq_sqes; } ____cacheline_aligned_in_smp; @@ -1291,7 +1290,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) INIT_LIST_HEAD(&ctx->iopoll_list); INIT_LIST_HEAD(&ctx->defer_list); INIT_LIST_HEAD(&ctx->timeout_list); - init_waitqueue_head(&ctx->inflight_wait); spin_lock_init(&ctx->inflight_lock); INIT_LIST_HEAD(&ctx->inflight_list); INIT_DELAYED_WORK(&ctx->file_put_work, io_file_put_work); @@ -6046,12 +6044,13 @@ static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe) static void io_req_drop_files(struct io_kiocb *req) { struct io_ring_ctx *ctx = req->ctx; + struct io_uring_task *tctx = req->task->io_uring; unsigned long flags; spin_lock_irqsave(&ctx->inflight_lock, flags); list_del(&req->inflight_entry); - if (waitqueue_active(&ctx->inflight_wait)) - wake_up(&ctx->inflight_wait); + if (atomic_read(&tctx->in_idle)) + wake_up(&tctx->wait); spin_unlock_irqrestore(&ctx->inflight_lock, flags); req->flags &= ~REQ_F_INFLIGHT; put_files_struct(req->work.identity->files); @@ -8693,8 +8692,8 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx, break; } if (found) - prepare_to_wait(&ctx->inflight_wait, &wait, - TASK_UNINTERRUPTIBLE); + prepare_to_wait(&task->io_uring->wait, &wait, + TASK_UNINTERRUPTIBLE); spin_unlock_irq(&ctx->inflight_lock); /* We need to keep going until we don't find a matching req */ @@ -8707,7 +8706,7 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx, /* cancellations _may_ trigger task work */ io_run_task_work(); schedule(); - finish_wait(&ctx->inflight_wait, &wait); + finish_wait(&task->io_uring->wait, &wait); } } -- 2.7.4