linux-kernel - [PATCH 4/5] io_uring: don't trigger timeout with another t-out

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <2fd19ca7ea8ce47a19802abf38d64a1460c9002f.1588253029.git.asml.silence@gmail.com>
Date:   Thu, 30 Apr 2020 22:31:09 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] io_uring: don't trigger timeout with another t-out

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@...il.com>
---
 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 006ac57af842..fb8ec4b00375 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_seq, start, end))
+		if (req->timeout.target_seq != 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_seq = tail + off;
 
 	/*
-- 
2.24.0