Dan Carpenter <dan.carpenter@xxxxxxxxxx> writes:
> 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.
Can you please also add a comment stating that irqs were disabled in
blkg_conf_prep? Otherwise future readers will surely be scratching
their heads trying to figure out why we do things two different ways in
the same function.
Thanks!
Jeff
>
> Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> block/blk-iocost.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-iocost.c b/block/blk-iocost.c
> index 2a3db80c1dce..a7ed434eae03 100644
> --- a/block/blk-iocost.c
> +++ b/block/blk-iocost.c
> @@ -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;
