[PATCH 2/7] block: Document more locking requirements

[Bart Van Assche]

This patch does not change any functionality.

Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Hannes Reinecke <h...@suse.de>
Cc: Johannes Thumshirn <jthumsh...@suse.de>
---
 block/blk-mq.c      | 13 +++++++++++--
 block/blk-timeout.c |  3 +++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e1ca7661daa5..7f290a91a612 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -74,6 +74,8 @@ static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx 
*hctx)
 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
                                     struct blk_mq_ctx *ctx)
 {
+       lockdep_assert_held(&ctx->lock);
+
        if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
                sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
 }
@@ -81,6 +83,8 @@ static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx 
*hctx,
 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
                                      struct blk_mq_ctx *ctx)
 {
+       lockdep_assert_held(&ctx->lock);
+
        sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
 }
 
@@ -1003,9 +1007,14 @@ bool blk_mq_get_driver_tag(struct request *rq, struct 
blk_mq_hw_ctx **hctx,
 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
                                int flags, void *key)
 {
-       struct blk_mq_hw_ctx *hctx;
+       struct blk_mq_hw_ctx *hctx =
+               container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
+
+#ifdef CONFIG_LOCKDEP
+       struct sbq_wait_state *ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
 
-       hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
+       lockdep_assert_held(&ws->wait.lock);
+#endif
 
        list_del_init(&wait->entry);
        blk_mq_run_hw_queue(hctx, true);
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 764ecf9aeb30..77bf0c6e7c7e 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -77,6 +77,9 @@ ssize_t part_timeout_store(struct device *dev, struct 
device_attribute *attr,
  */
 void blk_delete_timer(struct request *req)
 {
+       lockdep_assert_held(req->q->queue_lock);
+       WARN_ON_ONCE(req->q->mq_ops);
+
        list_del_init(&req->timeout_list);
 }
 
-- 
2.15.0