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io_uring: fix CQ waiting timeout handling

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Jiffy to ktime CQ waiting conversion broke how we treat timeouts, in
particular we rearm it anew every time we get into
io_cqring_wait_schedule() without adjusting the timeout. Waiting for 2
CQEs and getting a task_work in the middle may double the timeout value,
or even worse in some cases task may wait indefinitely.

Cc: stable@vger.kernel.org
Fixes: 228339662b ("io_uring: don't convert to jiffies for waiting on timeouts")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f7bffddd71b08f28a877d44d37ac953ddb01590d.1672915663.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-01-05 10:49:15 +00:00 committed by Jens Axboe
parent 59b745bb4e
commit 12521a5d5c
1 changed files with 3 additions and 3 deletions
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6
io_uring/io_uring.c
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@ -2470,7 +2470,7 @@ int io_run_task_work_sig(struct io_ring_ctx *ctx)
/* when returns >0, the caller should retry */ /* when returns >0, the caller should retry */
static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
struct io_wait_queue *iowq, struct io_wait_queue *iowq,
ktime_t timeout) ktime_t *timeout)
{ {
int ret; int ret;
unsigned long check_cq; unsigned long check_cq;
@ -2488,7 +2488,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
return -EBADR; return -EBADR;
} }
if (!schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS)) if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
return -ETIME; return -ETIME;
/* /*
@ -2564,7 +2564,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
} }
prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq, prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
TASK_INTERRUPTIBLE); TASK_INTERRUPTIBLE);
ret = io_cqring_wait_schedule(ctx, &iowq, timeout); ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
if (__io_cqring_events_user(ctx) >= min_events) if (__io_cqring_events_user(ctx) >= min_events)
break; break;
cond_resched(); cond_resched();