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From:   Marcos Paulo de Souza <marcos.souza.org@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     Marcos Paulo de Souza <marcos.souza.org@gmail.com>,
        Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org (open list:BLOCK LAYER)
Subject: [PATCH] blk-sysfs: Rework documention of __blk_release_queue
Date:   Wed, 30 Jan 2019 23:11:39 -0200
Message-Id: <20190131011139.2264742-1-marcos.souza.org@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The Notes section of the comment was removed, because now
blk_release_queue can only be executed from blk_cleanup_queue (being
called when the q->kobj reaches zero), and also blk_init_queue was removed
in a1ce35fa4985.

Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
---
 This is basically a v2 of https://lkml.org/lkml/2019/1/14/1098

 But, I tried to describe when this function is called, removing redundancies.
 Maybe it would be better placed in blk-core.c, where the q->kobj is initialized
 with blk_queue_ktype (which .release pointer points to blk_release_queue)?

 block/blk-sysfs.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 590d1ef2f961..d4dea9179fa6 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -817,21 +817,16 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head)
 }
 
 /**
- * __blk_release_queue - release a request queue when it is no longer needed
+ * __blk_release_queue - release a request queue
  * @work: pointer to the release_work member of the request queue to be released
  *
  * Description:
- *     blk_release_queue is the counterpart of blk_init_queue(). It should be
- *     called when a request queue is being released; typically when a block
- *     device is being de-registered. Its primary task it to free the queue
- *     itself.
- *
- * Notes:
- *     The low level driver must have finished any outstanding requests first
- *     via blk_cleanup_queue().
- *
- *     Although blk_release_queue() may be called with preemption disabled,
- *     __blk_release_queue() may sleep.
+ *     This function is called when a block device is being de-registered. The
+ *     process of releasing a request queue starts with blk_cleanup_queue, which
+ *     set the appropriate flags and the calls blk_put_queue, that decrements
+ *     the reference counter of the request queue. Once the reference counter
+ *     of the request queue reaches zero, blk_release_queue is called to release
+ *     all allocated resources of the request queue.
  */
 static void __blk_release_queue(struct work_struct *work)
 {
-- 
2.16.4