linux-kernel - [PATCH 16/16] block: reduce part_stat

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: <20200527052419.403583-17-hch@lst.de>
Date:   Wed, 27 May 2020 07:24:19 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>, dm-devel@...hat.com,
        linux-block@...r.kernel.org, drbd-dev@...ts.linbit.com,
        linux-bcache@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 16/16] block: reduce part_stat_lock() scope

We only need the stats lock (aka preempt_disable()) for updating the
states, not for looking up or dropping the hd_struct reference.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
 block/blk-core.c  | 5 +++--
 block/blk-merge.c | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index bf2f7d4bc0c1c..a01fb2b508f0e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1437,9 +1437,9 @@ void blk_account_io_done(struct request *req, u64 now)
 		update_io_ticks(part, jiffies, true);
 		part_stat_inc(part, ios[sgrp]);
 		part_stat_add(part, nsecs[sgrp], now - req->start_time_ns);
+		part_stat_unlock();
 
 		hd_struct_put(part);
-		part_stat_unlock();
 	}
 }
 
@@ -1448,8 +1448,9 @@ void blk_account_io_start(struct request *rq)
 	if (!blk_do_io_stat(rq))
 		return;
 
-	part_stat_lock();
 	rq->part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
+
+	part_stat_lock();
 	update_io_ticks(rq->part, jiffies, false);
 	part_stat_unlock();
 }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index c3beae5c1be71..f0b0bae075a0c 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -674,8 +674,9 @@ static void blk_account_io_merge_request(struct request *req)
 	if (blk_do_io_stat(req)) {
 		part_stat_lock();
 		part_stat_inc(req->part, merges[op_stat_group(req_op(req))]);
-		hd_struct_put(req->part);
 		part_stat_unlock();
+
+		hd_struct_put(req->part);
 	}
 }
 
-- 
2.26.2