Re: [PATCH] null_blk: cleanup null_init_tag_set

Re: [PATCH] null_blk: cleanup null_init_tag_set

[Sachin Sant]

I ran into similar[1] issue (addressed by this patch ) while running blktests and
can confirm that this patch fixes the reported problem for me.

Tested-by: Sachin Sant <sachinp@linux.ibm.com>

Thanks
- Sachin

[1] -> https://lore.kernel.org/linux-next/20220715124158.GA25618@test-zns/T/#t

Re: [PATCH] null_blk: cleanup null_init_tag_set

[Ming Lei]

On Fri, Jul 15, 2022 at 02:11:21PM +0000, Vincent Fu wrote:
> > -----Original Message-----
> > From: Ming Lei [mailto:ming.lei@redhat.com]
> > Sent: Thursday, July 14, 2022 11:19 PM
> > To: Jens Axboe <axboe@kernel.dk>
> > Cc: linux-block@vger.kernel.org; Ming Lei <ming.lei@redhat.com>;
> > Vincent Fu <vincent.fu@samsung.com>
> > 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@samsung.com>
> > Fixes: 37ae152c7a0d ("null_blk: add configfs variables for 2 options")
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >  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?

Yeah, it is right, and I have covered it in V2.

Thanks,
Ming

RE: [PATCH] null_blk: cleanup null_init_tag_set

[Vincent Fu]

> -----Original Message-----
> From: Ming Lei [mailto:ming.lei@redhat.com]
> Sent: Thursday, July 14, 2022 11:19 PM
> To: Jens Axboe <axboe@kernel.dk>
> Cc: linux-block@vger.kernel.org; Ming Lei <ming.lei@redhat.com>;
> Vincent Fu <vincent.fu@samsung.com>
> 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@samsung.com>
> Fixes: 37ae152c7a0d ("null_blk: add configfs variables for 2 options")
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  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

[PATCH] null_blk: cleanup null_init_tag_set

[Ming Lei]

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@samsung.com>
Fixes: 37ae152c7a0d ("null_blk: add configfs variables for 2 options")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 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;
+	}
+
 	set->ops = &null_mq_ops;
-	set->nr_hw_queues = nullb ? nullb->dev->submit_queues :
-						g_submit_queues;
-	poll_queues = nullb ? nullb->dev->poll_queues : g_poll_queues;
-	if (poll_queues)
-		set->nr_hw_queues += poll_queues;
-	set->queue_depth = nullb ? nullb->dev->hw_queue_depth :
-						g_hw_queue_depth;
-	set->numa_node = nullb ? nullb->dev->home_node : g_home_node;
 	set->cmd_size	= sizeof(struct nullb_cmd);
-	set->flags = BLK_MQ_F_SHOULD_MERGE;
-	if (nullb->dev->no_sched)
-		set->flags |= BLK_MQ_F_NO_SCHED;
-	if (nullb->dev->shared_tag_bitmap)
-		set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
+	set->flags = flags;
 	set->driver_data = nullb;
-	if (poll_queues)
+	set->nr_hw_queues = hw_queues;
+	set->queue_depth = queue_depth;
+	set->numa_node = numa_node;
+	if (poll_queues) {
+		set->nr_hw_queues += poll_queues;
 		set->nr_maps = 3;
-	else
+	} else {
 		set->nr_maps = 1;
-
-	if ((nullb && nullb->dev->blocking) || g_blocking)
-		set->flags |= BLK_MQ_F_BLOCKING;
+	}
 
 	return blk_mq_alloc_tag_set(set);
 }
-- 
2.31.1