on 2/23/2023 1:48 PM, Dan Carpenter wrote: > Hi Kemeng, > > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Kemeng-Shi/block-bfq-properly-mark-bfqq-remained-idle/20230219-104312 > base: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next > patch link: https://lore.kernel.org/r/20230219104309.1511562-18-shikemeng%40huaweicloud.com > patch subject: [PATCH 17/17] block, bfq: remove unnecessary local variable __bfqq in bfq_setup_merge > config: openrisc-randconfig-m041-20230219 (https://download.01.org/0day-ci/archive/20230220/202302200841.9zinyY7i-lkp@xxxxxxxxx/config) > compiler: or1k-linux-gcc (GCC) 12.1.0 > > If you fix the issue, kindly add following tag where applicable > | Reported-by: kernel test robot <lkp@xxxxxxxxx> > | Reported-by: Dan Carpenter <error27@xxxxxxxxx> > | Link: https://lore.kernel.org/r/202302200841.9zinyY7i-lkp@xxxxxxxxx/ > > New smatch warnings: > block/bfq-iosched.c:2785 bfq_setup_merge() error: we previously assumed 'new_bfqq' could be null (see line 2766) > > Old smatch warnings: > block/bfq-iosched.c:6195 __bfq_insert_request() warn: variable dereferenced before check 'bfqq' (see line 6191) > > vim +/new_bfqq +2785 block/bfq-iosched.c > > 36eca894832351 Arianna Avanzini 2017-04-12 2751 static struct bfq_queue * > 36eca894832351 Arianna Avanzini 2017-04-12 2752 bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) > 36eca894832351 Arianna Avanzini 2017-04-12 2753 { > 36eca894832351 Arianna Avanzini 2017-04-12 2754 int process_refs, new_process_refs; > 36eca894832351 Arianna Avanzini 2017-04-12 2755 > 36eca894832351 Arianna Avanzini 2017-04-12 2756 /* > 36eca894832351 Arianna Avanzini 2017-04-12 2757 * If there are no process references on the new_bfqq, then it is > 36eca894832351 Arianna Avanzini 2017-04-12 2758 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain > 36eca894832351 Arianna Avanzini 2017-04-12 2759 * may have dropped their last reference (not just their last process > 36eca894832351 Arianna Avanzini 2017-04-12 2760 * reference). > 36eca894832351 Arianna Avanzini 2017-04-12 2761 */ > 36eca894832351 Arianna Avanzini 2017-04-12 2762 if (!bfqq_process_refs(new_bfqq)) > 36eca894832351 Arianna Avanzini 2017-04-12 2763 return NULL; > 36eca894832351 Arianna Avanzini 2017-04-12 2764 > 36eca894832351 Arianna Avanzini 2017-04-12 2765 /* Avoid a circular list and skip interim queue merges. */ > 114533e1e26a36 Kemeng Shi 2023-02-19 @2766 while ((new_bfqq = new_bfqq->new_bfqq)) { > 114533e1e26a36 Kemeng Shi 2023-02-19 2767 if (new_bfqq == bfqq) > 36eca894832351 Arianna Avanzini 2017-04-12 2768 return NULL; > 36eca894832351 Arianna Avanzini 2017-04-12 2769 } > > This now loops until new_bfqq is NULL. > > 36eca894832351 Arianna Avanzini 2017-04-12 2770 > 36eca894832351 Arianna Avanzini 2017-04-12 2771 process_refs = bfqq_process_refs(bfqq); > 36eca894832351 Arianna Avanzini 2017-04-12 2772 new_process_refs = bfqq_process_refs(new_bfqq); > > What?Sorry, I didn't expect that there is a behavior change. I will drop this one in next version. Thanks. -- Best wishes Kemeng Shi
