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: <20250730082207.4031744-2-yukuai1@huaweicloud.com>
Date: Wed, 30 Jul 2025 16:22:03 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: dlemoal@...nel.org,
	hare@...e.de,
	jack@...e.cz,
	tj@...nel.org,
	josef@...icpanda.com,
	axboe@...nel.dk,
	yukuai3@...wei.com
Cc: cgroups@...r.kernel.org,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	yukuai1@...weicloud.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	johnny.chenyi@...wei.com
Subject: [PATCH v2 1/5] blk-mq-sched: introduce high level elevator lock

From: Yu Kuai <yukuai3@...wei.com>

Currently, both mq-deadline and bfq have global spin lock that will be
grabbed inside elevator methods like dispatch_request, insert_requests,
and bio_merge. And the global lock is the main reason mq-deadline and
bfq can't scale very well.

While dispatching request, blk_mq_get_disatpch_budget() and
blk_mq_get_driver_tag() must be called, and they are not ready to be called
inside elevator methods, hence introduce a new method like
dispatch_requests is not possible.

Hence introduce a new high level elevator lock, currently it is protecting
dispatch_request only. Following patches will convert mq-deadline and bfq
to use this lock and finally support request batch dispatching by calling
the method multiple time while holding the lock.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 block/blk-mq-sched.c | 6 ++++++
 block/elevator.c     | 1 +
 block/elevator.h     | 4 ++--
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 55a0fd105147..7911fae75ce4 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -98,6 +98,7 @@ static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
 		max_dispatch = hctx->queue->nr_requests;
 
 	do {
+		bool sq_sched = blk_queue_sq_sched(q);
 		struct request *rq;
 		int budget_token;
 
@@ -113,7 +114,12 @@ static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
 		if (budget_token < 0)
 			break;
 
+		if (sq_sched)
+			spin_lock(&e->lock);
 		rq = e->type->ops.dispatch_request(hctx);
+		if (sq_sched)
+			spin_unlock(&e->lock);
+
 		if (!rq) {
 			blk_mq_put_dispatch_budget(q, budget_token);
 			/*
diff --git a/block/elevator.c b/block/elevator.c
index 88f8f36bed98..45303af0ca73 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -144,6 +144,7 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
 	eq->type = e;
 	kobject_init(&eq->kobj, &elv_ktype);
 	mutex_init(&eq->sysfs_lock);
+	spin_lock_init(&eq->lock);
 	hash_init(eq->hash);
 
 	return eq;
diff --git a/block/elevator.h b/block/elevator.h
index a07ce773a38f..cbbac4f7825c 100644
--- a/block/elevator.h
+++ b/block/elevator.h
@@ -110,12 +110,12 @@ struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 /*
  * each queue has an elevator_queue associated with it
  */
-struct elevator_queue
-{
+struct elevator_queue {
 	struct elevator_type *type;
 	void *elevator_data;
 	struct kobject kobj;
 	struct mutex sysfs_lock;
+	spinlock_t lock;
 	unsigned long flags;
 	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 };
-- 
2.39.2


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ