[PATCH v4] block: add BLK_MQ_POLL_CLASSIC for hybrid poll and return EINVAL for unexpected value

[PATCH v4] block: add BLK_MQ_POLL_CLASSIC for hybrid poll and return EINVAL for unexpected value

[Yufen Yu]

For q->poll_nsec == -1, means doing classic poll, not hybrid poll.
We introduce a new flag BLK_MQ_POLL_CLASSIC to replace -1, which
may make code much easier to read.

Additionally, since val is an int obtained with kstrtoint(), val can be
a negative value other than -1, so return -EINVAL for that case.

Thanks to Damien Le Moal for some good suggestion.

Signed-off-by: Yufen Yu <yuyufen@huawei.com>
---
 block/blk-mq.c         |  4 ++--
 block/blk-sysfs.c      | 12 +++++++-----
 include/linux/blkdev.h |  3 +++
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a9c181603cbd..1c588e5c4a02 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2857,7 +2857,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	/*
 	 * Default to classic polling
 	 */
-	q->poll_nsec = -1;
+	q->poll_nsec = BLK_MQ_POLL_CLASSIC;
 
 	blk_mq_init_cpu_queues(q, set->nr_hw_queues);
 	blk_mq_add_queue_tag_set(set, q);
@@ -3392,7 +3392,7 @@ static bool blk_mq_poll_hybrid(struct request_queue *q,
 {
 	struct request *rq;
 
-	if (q->poll_nsec == -1)
+	if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
 		return false;
 
 	if (!blk_qc_t_is_internal(cookie))
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 59685918167e..422327089e0f 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -360,8 +360,8 @@ static ssize_t queue_poll_delay_show(struct request_queue *q, char *page)
 {
 	int val;
 
-	if (q->poll_nsec == -1)
-		val = -1;
+	if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
+		val = BLK_MQ_POLL_CLASSIC;
 	else
 		val = q->poll_nsec / 1000;
 
@@ -380,10 +380,12 @@ static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
 	if (err < 0)
 		return err;
 
-	if (val == -1)
-		q->poll_nsec = -1;
-	else
+	if (val == BLK_MQ_POLL_CLASSIC)
+		q->poll_nsec = BLK_MQ_POLL_CLASSIC;
+	else if (val >= 0)
 		q->poll_nsec = val * 1000;
+	else
+		return -EINVAL;
 
 	return count;
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0de92b29f589..5c58a3b2bf00 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -50,6 +50,9 @@ struct blk_stat_callback;
 /* Must be consistent with blk_mq_poll_stats_bkt() */
 #define BLK_MQ_POLL_STATS_BKTS 16
 
+/* Doing classic polling */
+#define BLK_MQ_POLL_CLASSIC -1
+
 /*
  * Maximum number of blkcg policies allowed to be registered concurrently.
  * Defined here to simplify include dependency.
-- 
2.16.2.dirty

Re: [PATCH v4] block: add BLK_MQ_POLL_CLASSIC for hybrid poll and return EINVAL for unexpected value

[Damien Le Moal]

On 2019/03/18 23:40, Yufen Yu wrote:
> For q->poll_nsec == -1, means doing classic poll, not hybrid poll.
> We introduce a new flag BLK_MQ_POLL_CLASSIC to replace -1, which
> may make code much easier to read.
> 
> Additionally, since val is an int obtained with kstrtoint(), val can be
> a negative value other than -1, so return -EINVAL for that case.
> 
> Thanks to Damien Le Moal for some good suggestion.
> 
> Signed-off-by: Yufen Yu <yuyufen@huawei.com>
> ---
>  block/blk-mq.c         |  4 ++--
>  block/blk-sysfs.c      | 12 +++++++-----
>  include/linux/blkdev.h |  3 +++
>  3 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index a9c181603cbd..1c588e5c4a02 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2857,7 +2857,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
>  	/*
>  	 * Default to classic polling
>  	 */
> -	q->poll_nsec = -1;
> +	q->poll_nsec = BLK_MQ_POLL_CLASSIC;
>  
>  	blk_mq_init_cpu_queues(q, set->nr_hw_queues);
>  	blk_mq_add_queue_tag_set(set, q);
> @@ -3392,7 +3392,7 @@ static bool blk_mq_poll_hybrid(struct request_queue *q,
>  {
>  	struct request *rq;
>  
> -	if (q->poll_nsec == -1)
> +	if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
>  		return false;
>  
>  	if (!blk_qc_t_is_internal(cookie))
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 59685918167e..422327089e0f 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -360,8 +360,8 @@ static ssize_t queue_poll_delay_show(struct request_queue *q, char *page)
>  {
>  	int val;
>  
> -	if (q->poll_nsec == -1)
> -		val = -1;
> +	if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
> +		val = BLK_MQ_POLL_CLASSIC;
>  	else
>  		val = q->poll_nsec / 1000;
>  
> @@ -380,10 +380,12 @@ static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
>  	if (err < 0)
>  		return err;
>  
> -	if (val == -1)
> -		q->poll_nsec = -1;
> -	else
> +	if (val == BLK_MQ_POLL_CLASSIC)
> +		q->poll_nsec = BLK_MQ_POLL_CLASSIC;
> +	else if (val >= 0)
>  		q->poll_nsec = val * 1000;
> +	else
> +		return -EINVAL;
>  
>  	return count;
>  }
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 0de92b29f589..5c58a3b2bf00 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -50,6 +50,9 @@ struct blk_stat_callback;
>  /* Must be consistent with blk_mq_poll_stats_bkt() */
>  #define BLK_MQ_POLL_STATS_BKTS 16
>  
> +/* Doing classic polling */
> +#define BLK_MQ_POLL_CLASSIC -1
> +
>  /*
>   * Maximum number of blkcg policies allowed to be registered concurrently.
>   * Defined here to simplify include dependency.
> 

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>

-- 
Damien Le Moal
Western Digital Research

Re: [PATCH v4] block: add BLK_MQ_POLL_CLASSIC for hybrid poll and return EINVAL for unexpected value

[Jens Axboe]

On 3/18/19 8:44 AM, Yufen Yu wrote:
> For q->poll_nsec == -1, means doing classic poll, not hybrid poll.
> We introduce a new flag BLK_MQ_POLL_CLASSIC to replace -1, which
> may make code much easier to read.
> 
> Additionally, since val is an int obtained with kstrtoint(), val can be
> a negative value other than -1, so return -EINVAL for that case.

Applied, thanks.

-- 
Jens Axboe