From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 1/1] io_uring: replace inflight_wait with tctx->wait
Date: Sun, 15 Nov 2020 12:56:32 +0000 [thread overview]
Message-ID: <ce4f91e603b524b6425d68cf49c83c7d4fbd7d79.1605444955.git.asml.silence@gmail.com> (raw)
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 <[email protected]>
---
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 feb8e5bd2fb2..1a7ac86a0b92 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -286,7 +286,6 @@ 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;
@@ -1300,7 +1299,6 @@ 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);
@@ -6081,12 +6079,13 @@ 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);
@@ -8721,8 +8720,8 @@ 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 */
@@ -8735,7 +8734,7 @@ 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);
}
}
--
2.24.0
next reply other threads:[~2020-11-15 13:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-15 12:56 Pavel Begunkov [this message]
2020-11-16 16:33 ` [PATCH 1/1] io_uring: replace inflight_wait with tctx->wait Jens Axboe
2020-11-16 16:48 ` Pavel Begunkov
2020-11-16 16:57 ` Jens Axboe
2020-11-16 17:16 ` Pavel Begunkov
2020-11-16 20:42 ` Jens Axboe
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