linux-kernel - [PATCH v5 2/7] block: clarify context for gendisk / request

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Date:   Sat, 16 May 2020 03:19:51 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     axboe@...nel.dk, viro@...iv.linux.org.uk, bvanassche@....org,
        gregkh@...uxfoundation.org, rostedt@...dmis.org, mingo@...hat.com,
        jack@...e.cz, ming.lei@...hat.com, nstange@...e.de,
        akpm@...ux-foundation.org
Cc:     mhocko@...e.com, yukuai3@...wei.com, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Luis Chamberlain <mcgrof@...nel.org>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v5 2/7] block: clarify context for gendisk / request_queue refcount increment helpers

Let us clarify the context under which the helpers to increment the
refcount for the gendisk and request_queue can be called under. We
make this explicit on the places where we may sleep with might_sleep().

We don't address the decrement context yet, as that needs some extra
work and fixes, but will be addressed in the next patch.

Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 block/blk-core.c | 2 ++
 block/genhd.c    | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index e438c3b0815b..94216fa16a05 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -610,6 +610,8 @@ EXPORT_SYMBOL(blk_alloc_queue);
  * @q: the request_queue structure to increment the refcount for
  *
  * Increment the refcount of the request_queue kobject.
+ *
+ * Context: Any context.
  */
 bool blk_get_queue(struct request_queue *q)
 {
diff --git a/block/genhd.c b/block/genhd.c
index af910e6a0233..598bd32ad28c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1017,11 +1017,15 @@ static ssize_t disk_badblocks_store(struct device *dev,
  *
  * This function gets the structure containing partitioning
  * information for the given device @devt.
+ *
+ * Context: can sleep
  */
 struct gendisk *get_gendisk(dev_t devt, int *partno)
 {
 	struct gendisk *disk = NULL;
 
+	might_sleep();
+
 	if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
 		struct kobject *kobj;
 
@@ -1785,6 +1789,8 @@ EXPORT_SYMBOL(__alloc_disk_node);
  *
  * This increments the refcount for the struct gendisk, and the gendisk's
  * fops module owner.
+ *
+ * Context: Any context.
  */
 struct kobject *get_disk_and_module(struct gendisk *disk)
 {
-- 
2.26.2