Commit 41591a51 authored Oct 31, 2019 by Dan Carpenter Committed by Jens Axboe Oct 31, 2019

iocost: don't nest spin_lock_irq in ioc_weight_write()



This code causes a static analysis warning:

    block/blk-iocost.c:2113 ioc_weight_write() error: double lock 'irq'

We disable IRQs in blkg_conf_prep() and re-enable them in
blkg_conf_finish().  IRQ disable/enable should not be nested because
that means the IRQs will be enabled at the first unlock instead of the
second one.

Fixes: 7caa4715 ("blkcg: implement blk-iocost")
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 6873e0bd

block/blk-iocost.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2110,10 +2110,10 @@ static ssize_t ioc_weight_write(struct kernfs_open_file of, char buf,
		goto einval;
		}

		spin_lock_irq(&iocg->ioc->lock);
		spin_lock(&iocg->ioc->lock);
		iocg->cfg_weight = v;
		weight_updated(iocg);
		spin_unlock_irq(&iocg->ioc->lock);
		spin_unlock(&iocg->ioc->lock);

		blkg_conf_finish(&ctx);
		return nbytes;

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