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Message-ID: <20191104101811.GA20821@mwanda>
Date: Mon, 4 Nov 2019 13:18:11 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: Jens Axboe <axboe@...nel.dk>, Jeff Moyer <jmoyer@...hat.com>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-janitors@...r.kernel.org
Subject: [PATCH] iocost: add a comment about locking in ioc_weight_write()
It wasn't very clear that blkg_conf_prep() disables IRQ and that they
are enabled in blkg_conf_finish() so this patch adds a comment about it.
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
I don't know if it's too late to fold this in with the previous patch?
block/blk-iocost.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index a7ed434eae03..c5a8703ca6aa 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -2095,6 +2095,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
return nbytes;
}
+ /* blkg_conf_prep() takes the q->queue_lock and disables IRQs */
ret = blkg_conf_prep(blkcg, &blkcg_policy_iocost, buf, &ctx);
if (ret)
return ret;
@@ -2115,6 +2116,7 @@ static ssize_t ioc_weight_write(struct kernfs_open_file *of, char *buf,
weight_updated(iocg);
spin_unlock(&iocg->ioc->lock);
+ /* blkg_conf_finish() unlocks the q->queue_lock and enables IRQs */
blkg_conf_finish(&ctx);
return nbytes;
--
2.20.1
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