linux-kernel - [RFC PATCH 2/2] bfq/mq-deadline: remove redundant check for passthrough request

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-next>] [day] [month] [year] [list]

Message-Id: <20210415034326.214227-1-linf@wangsu.com>
Date:   Thu, 15 Apr 2021 11:43:26 +0800
From:   Lin Feng <linf@...gsu.com>
To:     axboe@...nel.dk, paolo.valente@...aro.org
Cc:     linux-block@...r.kernel.org, ming.lei@...hat.com, linf@...gsu.com,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH 2/2] bfq/mq-deadline: remove redundant check for passthrough request

Since commit 01e99aeca39796003 'blk-mq: insert passthrough request into
hctx->dispatch directly', passthrough request should not appear in
IO-scheduler any more, so blk_rq_is_passthrough checking in addon IO
schedulers is redundant.

(Notes: this patch passes generic IO load test with hdds under SAS
controller and hdds under AHCI controller but obviously not covers all.
Not sure if passthrough request can still escape into IO scheduler from
blk_mq_sched_insert_requests, which is used by blk_mq_flush_plug_list and
has lots of indirect callers.)

Signed-off-by: Lin Feng <linf@...gsu.com>
---
 block/bfq-iosched.c | 2 +-
 block/mq-deadline.c | 7 ++-----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 95586137194e..b827c9212b02 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5627,7 +5627,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 
 	spin_lock_irq(&bfqd->lock);
 	bfqq = bfq_init_rq(rq);
-	if (!bfqq || at_head || blk_rq_is_passthrough(rq)) {
+	if (!bfqq || at_head) {
 		if (at_head)
 			list_add(&rq->queuelist, &bfqd->dispatch);
 		else
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index f3631a287466..04aded71ead2 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -500,11 +500,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 
 	trace_block_rq_insert(rq);
 
-	if (at_head || blk_rq_is_passthrough(rq)) {
-		if (at_head)
-			list_add(&rq->queuelist, &dd->dispatch);
-		else
-			list_add_tail(&rq->queuelist, &dd->dispatch);
+	if (at_head) {
+		list_add(&rq->queuelist, &dd->dispatch);
 	} else {
 		deadline_add_rq_rb(dd, rq);
 
-- 
2.30.2