Skip to content

Commit

Permalink
block: Document what queue type each function is intended for
Browse files Browse the repository at this point in the history 
Some functions in block/blk-core.c must only be used on blk-sq queues
while others are safe to use against any queue type. Document which
functions are intended for blk-sq queues and issue a warning if the
blk-sq API is misused. This does not only help block driver authors
but will also make it easier to remove the blk-sq code once that code
is declared obsolete.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
  • Loading branch information
@axboe
Bart Van Assche authored and axboe committed Jun 21, 2017
1 parent 2fff8a9 commit 332ebbf
Show file tree
Hide file tree
Showing 2 changed files with 35 additions and 0 deletions.
33 changes: 33 additions & 0 deletions block/blk-core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -241,6 +241,7 @@ static void blk_delay_work(struct work_struct *work)
void blk_delay_queue(struct request_queue *q, unsigned long msecs)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

if (likely(!blk_queue_dead(q)))
queue_delayed_work(kblockd_workqueue, &q->delay_work,
Expand All @@ -260,6 +261,7 @@ EXPORT_SYMBOL(blk_delay_queue);
void blk_start_queue_async(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

queue_flag_clear(QUEUE_FLAG_STOPPED, q);
blk_run_queue_async(q);
Expand All @@ -279,6 +281,7 @@ void blk_start_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON(!irqs_disabled());
WARN_ON_ONCE(q->mq_ops);

queue_flag_clear(QUEUE_FLAG_STOPPED, q);
__blk_run_queue(q);
Expand All @@ -302,6 +305,7 @@ EXPORT_SYMBOL(blk_start_queue);
void blk_stop_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

cancel_delayed_work(&q->delay_work);
queue_flag_set(QUEUE_FLAG_STOPPED, q);
Expand Down Expand Up @@ -356,6 +360,7 @@ EXPORT_SYMBOL(blk_sync_queue);
inline void __blk_run_queue_uncond(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

if (unlikely(blk_queue_dead(q)))
return;
Expand Down Expand Up @@ -383,6 +388,7 @@ EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
void __blk_run_queue(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

if (unlikely(blk_queue_stopped(q)))
return;
Expand All @@ -407,6 +413,7 @@ EXPORT_SYMBOL(__blk_run_queue);
void blk_run_queue_async(struct request_queue *q)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
Expand All @@ -425,6 +432,8 @@ void blk_run_queue(struct request_queue *q)
{
unsigned long flags;

WARN_ON_ONCE(q->mq_ops);

spin_lock_irqsave(q->queue_lock, flags);
__blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
Expand Down Expand Up @@ -453,6 +462,7 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
int i;

lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

while (true) {
bool drain = false;
Expand Down Expand Up @@ -531,6 +541,8 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
*/
void blk_queue_bypass_start(struct request_queue *q)
{
WARN_ON_ONCE(q->mq_ops);

spin_lock_irq(q->queue_lock);
q->bypass_depth++;
queue_flag_set(QUEUE_FLAG_BYPASS, q);
Expand All @@ -557,6 +569,9 @@ EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
* @q: queue of interest
*
* Leave bypass mode and restore the normal queueing behavior.
*
* Note: although blk_queue_bypass_start() is only called for blk-sq queues,
* this function is called for both blk-sq and blk-mq queues.
*/
void blk_queue_bypass_end(struct request_queue *q)
{
Expand Down Expand Up @@ -954,6 +969,8 @@ static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);

int blk_init_allocated_queue(struct request_queue *q)
{
WARN_ON_ONCE(q->mq_ops);

q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size);
if (!q->fq)
return -ENOMEM;
Expand Down Expand Up @@ -1091,6 +1108,8 @@ int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
struct request_list *rl;
int on_thresh, off_thresh;

WARN_ON_ONCE(q->mq_ops);

spin_lock_irq(q->queue_lock);
q->nr_requests = nr;
blk_queue_congestion_threshold(q);
Expand Down Expand Up @@ -1329,6 +1348,7 @@ static struct request *get_request(struct request_queue *q, unsigned int op,
struct request *rq;

lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

rl = blk_get_rl(q, bio); /* transferred to @rq on success */
retry:
Expand Down Expand Up @@ -1373,6 +1393,8 @@ static struct request *blk_old_get_request(struct request_queue *q,
{
struct request *rq;

WARN_ON_ONCE(q->mq_ops);

/* create ioc upfront */
create_io_context(gfp_mask, q->node);

Expand Down Expand Up @@ -1424,6 +1446,7 @@ EXPORT_SYMBOL(blk_get_request);
void blk_requeue_request(struct request_queue *q, struct request *rq)
{
lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

blk_delete_timer(rq);
blk_clear_rq_complete(rq);
Expand Down Expand Up @@ -2495,6 +2518,7 @@ struct request *blk_peek_request(struct request_queue *q)
int ret;

lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

while ((rq = __elv_next_request(q)) != NULL) {

Expand Down Expand Up @@ -2615,6 +2639,7 @@ void blk_dequeue_request(struct request *rq)
void blk_start_request(struct request *req)
{
lockdep_assert_held(req->q->queue_lock);
WARN_ON_ONCE(req->q->mq_ops);

blk_dequeue_request(req);

Expand Down Expand Up @@ -2646,6 +2671,7 @@ struct request *blk_fetch_request(struct request_queue *q)
struct request *rq;

lockdep_assert_held(q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

rq = blk_peek_request(q);
if (rq)
Expand Down Expand Up @@ -2797,6 +2823,7 @@ void blk_finish_request(struct request *req, blk_status_t error)
struct request_queue *q = req->q;

lockdep_assert_held(req->q->queue_lock);
WARN_ON_ONCE(q->mq_ops);

if (req->rq_flags & RQF_STATS)
blk_stat_add(req);
Expand Down Expand Up @@ -2851,6 +2878,8 @@ static bool blk_end_bidi_request(struct request *rq, blk_status_t error,
struct request_queue *q = rq->q;
unsigned long flags;

WARN_ON_ONCE(q->mq_ops);

if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
return true;

Expand Down Expand Up @@ -2880,6 +2909,7 @@ static bool __blk_end_bidi_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes, unsigned int bidi_bytes)
{
lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);

if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
return true;
Expand All @@ -2906,6 +2936,7 @@ static bool __blk_end_bidi_request(struct request *rq, blk_status_t error,
bool blk_end_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes)
{
WARN_ON_ONCE(rq->q->mq_ops);
return blk_end_bidi_request(rq, error, nr_bytes, 0);
}
EXPORT_SYMBOL(blk_end_request);
Expand Down Expand Up @@ -2948,6 +2979,7 @@ bool __blk_end_request(struct request *rq, blk_status_t error,
unsigned int nr_bytes)
{
lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);

return __blk_end_bidi_request(rq, error, nr_bytes, 0);
}
Expand All @@ -2967,6 +2999,7 @@ void __blk_end_request_all(struct request *rq, blk_status_t error)
unsigned int bidi_bytes = 0;

lockdep_assert_held(rq->q->queue_lock);
WARN_ON_ONCE(rq->q->mq_ops);

if (unlikely(blk_bidi_rq(rq)))
bidi_bytes = blk_rq_bytes(rq->next_rq);
Expand Down
2 changes: 2 additions & 0 deletions block/blk.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,8 @@ static inline struct request *__elv_next_request(struct request_queue *q)
struct request *rq;
struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);

WARN_ON_ONCE(q->mq_ops);

while (1) {
if (!list_empty(&q->queue_head)) {
rq = list_entry_rq(q->queue_head.next);
Expand Down

0 comments on commit 332ebbf

Please sign in to comment.