linux-kernel - [PATCH 3/7] blk-mq: Fix disabled hybrid polling

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: <87e3f35a44cf987cc71a8dcc38238bc61164fb11.1556609582.git.asml.silence@gmail.com>
Date:   Tue, 30 Apr 2019 10:34:15 +0300
From:   "Pavel Begunkov (Silence)" <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Pavel Begunkov <asml.silence@...il.com>
Subject: [PATCH 3/7] blk-mq: Fix disabled hybrid polling

From: Pavel Begunkov <asml.silence@...il.com>

Commit 4bc6339a583cec650b05 ("block: move blk_stat_add() to
__blk_mq_end_request()") moved blk_stat_add(), so now it's called after
blk_update_request(), which zeroes rq->__data_len. Without length,
blk_stat_add() can't calculate stat bucket and returns error,
effectively disabling hybrid polling.

Move it back to __blk_mq_complete_request.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 block/blk-mq.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index fc60ed7e940e..cc3f73e4e01c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -535,11 +535,6 @@ inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
 	if (blk_mq_need_time_stamp(rq))
 		now = ktime_get_ns();
 
-	if (rq->rq_flags & RQF_STATS) {
-		blk_mq_poll_stats_start(rq->q);
-		blk_stat_add(rq, now);
-	}
-
 	if (rq->internal_tag != -1)
 		blk_mq_sched_completed_request(rq, now);
 
@@ -578,6 +573,11 @@ static void __blk_mq_complete_request(struct request *rq)
 	int cpu;
 
 	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
+
+	if (rq->rq_flags & RQF_STATS) {
+		blk_mq_poll_stats_start(rq->q);
+		blk_stat_add(rq, ktime_get_ns());
+	}
 	/*
 	 * Most of single queue controllers, there is only one irq vector
 	 * for handling IO completion, and the only irq's affinity is set
-- 
2.21.0