Re: [PATCH v3] block: add a new flag BLK_MQ_POLL_CLASSIC for hybrid poll

[yuyufen]

On 2019/3/16 0:11, Damien Le Moal wrote:

On 2019/03/14 21:19, 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.

Signed-off-by: Yufen Yu <yuyu...@huawei.com>
---
  block/blk-mq.c         | 4 ++--
  block/blk-sysfs.c      | 8 ++++----
  include/linux/blkdev.h | 3 +++
  3 files changed, 9 insertions(+), 6 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..cd127067998a 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;

@@ -380,8 +380,8 @@ 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;
+       if (val == BLK_MQ_POLL_CLASSIC)
+               q->poll_nsec = BLK_MQ_POLL_CLASSIC;
        else
                q->poll_nsec = val * 1000;

You are not handling negative values other than -1 here as we discussed. Any
reason for not adding the check ?

Oops, I send the wrong version.
Thanks again for your review and suggestion.

Yufen.
thanks

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.