[PATCH 2/2] io_uring: don't trigger timeout with another t-out

From: Pavel Begunkov
Date: Sat Apr 18 2020 - 13:21:32 EST


When deciding whether to fire a timeout basing on number of completions,
ignore CQEs emitted by other timeouts.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
fs/io_uring.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index c34c5dcc90fc..d72f82c09ce3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1098,33 +1098,20 @@ static void io_kill_timeouts(struct io_ring_ctx *ctx)
spin_unlock_irq(&ctx->completion_lock);
}

-static inline bool io_check_in_range(u32 pos, u32 start, u32 end)
-{
- /* if @end < @start, check for [end, MAX_UINT] + [MAX_UINT, start] */
- return (pos - start) <= (end - start);
-}
-
static void __io_flush_timeouts(struct io_ring_ctx *ctx)
{
- u32 end, start;
-
- start = end = ctx->cached_cq_tail;
do {
struct io_kiocb *req = list_first_entry(&ctx->timeout_list,
struct io_kiocb, list);

if (req->flags & REQ_F_TIMEOUT_NOSEQ)
break;
- /*
- * multiple timeouts may have the same target,
- * check that @req is in [first_tail, cur_tail]
- */
- if (!io_check_in_range(req->timeout.target_cq, start, end))
+ if (req->timeout.target_cq != ctx->cached_cq_tail
+ - atomic_read(&ctx->cq_timeouts))
break;

list_del_init(&req->list);
io_kill_timeout(req);
- end = ctx->cached_cq_tail;
} while (!list_empty(&ctx->timeout_list));
}

@@ -4688,7 +4675,7 @@ static int io_timeout(struct io_kiocb *req)
goto add;
}

- tail = ctx->cached_cq_tail;
+ tail = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
req->timeout.target_cq = tail + off;

/*
--
2.24.0