> -----Original Message----- > From: Ming Lei [mailto:ming.lei@xxxxxxxxxx] > Sent: Thursday, July 14, 2022 11:19 PM > To: Jens Axboe <axboe@xxxxxxxxx> > Cc: linux-block@xxxxxxxxxxxxxxx; Ming Lei <ming.lei@xxxxxxxxxx>; > Vincent Fu <vincent.fu@xxxxxxxxxxx> > Subject: [PATCH] null_blk: cleanup null_init_tag_set > > The passed 'nullb' can be NULL, so cause null ptr reference. > > Fix the issue, meantime cleanup null_init_tag_set for avoiding to add > similar issue in future. > > Cc: Vincent Fu <vincent.fu@xxxxxxxxxxx> > Fixes: 37ae152c7a0d ("null_blk: add configfs variables for 2 options") > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > drivers/block/null_blk/main.c | 49 ++++++++++++++++++++++----------- > -- > 1 file changed, 31 insertions(+), 18 deletions(-) > > diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c > index c955a07dba2d..a08856b121b3 100644 > --- a/drivers/block/null_blk/main.c > +++ b/drivers/block/null_blk/main.c > @@ -1898,31 +1898,44 @@ static int null_gendisk_register(struct nullb > *nullb) > > static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set > *set) > { > + unsigned int flags = BLK_MQ_F_SHOULD_MERGE; > + int hw_queues, numa_node; > + unsigned int queue_depth; > int poll_queues; > > + if (nullb) { > + hw_queues = nullb->dev->submit_queues; > + poll_queues = nullb->dev->poll_queues; > + queue_depth = nullb->dev->hw_queue_depth; > + numa_node = nullb->dev->home_node; > + if (nullb->dev->no_sched) > + flags |= BLK_MQ_F_NO_SCHED; > + if (nullb->dev->shared_tag_bitmap) > + flags |= BLK_MQ_F_TAG_HCTX_SHARED; > + if (nullb->dev->blocking) > + flags |= BLK_MQ_F_BLOCKING; > + } else { > + hw_queues = g_submit_queues; > + poll_queues = g_poll_queues; > + queue_depth = g_hw_queue_depth; > + numa_node = g_home_node; > + if (g_blocking) > + flags |= BLK_MQ_F_BLOCKING; > + } > + Ming, thank you for fixing the mess I created. I believe that even when 'nullb' is NULL we should still set the BLK_MQ_F_NO_SCHED and BLK_MQ_F_TAG_HCTX_SHARED flags based on the values of g_no_sched and g_shared_tag_bitmap, respectively. Is that not right? Vincent
