From: Coly Li Date: Wed, 13 Nov 2019 08:03:17 +0000 (+0800) Subject: bcache: fix static checker warning in bcache_device_free() X-Git-Tag: v5.15~5119^2~11 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2d8869518a525c9bce5f5268419df9dfbe3dfdeb;p=platform%2Fkernel%2Flinux-starfive.git bcache: fix static checker warning in bcache_device_free() Commit cafe56359144 ("bcache: A block layer cache") leads to the following static checker warning: ./drivers/md/bcache/super.c:770 bcache_device_free() warn: variable dereferenced before check 'd->disk' (see line 766) drivers/md/bcache/super.c 762 static void bcache_device_free(struct bcache_device *d) 763 { 764 lockdep_assert_held(&bch_register_lock); 765 766 pr_info("%s stopped", d->disk->disk_name); ^^^^^^^^^ Unchecked dereference. 767 768 if (d->c) 769 bcache_device_detach(d); 770 if (d->disk && d->disk->flags & GENHD_FL_UP) ^^^^^^^ Check too late. 771 del_gendisk(d->disk); 772 if (d->disk && d->disk->queue) 773 blk_cleanup_queue(d->disk->queue); 774 if (d->disk) { 775 ida_simple_remove(&bcache_device_idx, 776 first_minor_to_idx(d->disk->first_minor)); 777 put_disk(d->disk); 778 } 779 It is not 100% sure that the gendisk struct of bcache device will always be there, the warning makes sense when there is problem in block core. This patch tries to remove the static checking warning by checking d->disk to avoid NULL pointer deferences. Reported-by: Dan Carpenter Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index ebb854e..7becced 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -761,20 +761,28 @@ static inline int idx_to_first_minor(int idx) static void bcache_device_free(struct bcache_device *d) { + struct gendisk *disk = d->disk; + lockdep_assert_held(&bch_register_lock); - pr_info("%s stopped", d->disk->disk_name); + if (disk) + pr_info("%s stopped", disk->disk_name); + else + pr_err("bcache device (NULL gendisk) stopped"); if (d->c) bcache_device_detach(d); - if (d->disk && d->disk->flags & GENHD_FL_UP) - del_gendisk(d->disk); - if (d->disk && d->disk->queue) - blk_cleanup_queue(d->disk->queue); - if (d->disk) { + + if (disk) { + if (disk->flags & GENHD_FL_UP) + del_gendisk(disk); + + if (disk->queue) + blk_cleanup_queue(disk->queue); + ida_simple_remove(&bcache_device_idx, - first_minor_to_idx(d->disk->first_minor)); - put_disk(d->disk); + first_minor_to_idx(disk->first_minor)); + put_disk(disk); } bioset_exit(&d->bio_split);