If a user of sbitmap limits the shallow depth on his own, then we need to inform the lower layers. Otherwise we can run into a situation where the user has limited the depth to something smaller than our wake batch count, which can cause hangs.
Signed-off-by: Jens Axboe <[email protected]> --- include/linux/sbitmap.h | 11 +++++++++++ lib/sbitmap.c | 17 ++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index 841585f6e5f2..99059789f45f 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -164,6 +164,17 @@ static inline void sbitmap_free(struct sbitmap *sb) void sbitmap_resize(struct sbitmap *sb, unsigned int depth); /** + * sbitmap_queue_shallow_depth() - Inform sbitmap about shallow depth changes + * @sbq: Bitmap queue in question + * @depth: Shallow depth limit + * + * Due to how sbitmap does batched wakes, if a user of sbitmap updates the + * shallow depth, then we might need to update our batched wake counts. + * + */ +void sbitmap_queue_shallow_depth(struct sbitmap_queue *sbq, unsigned int depth); + +/** * sbitmap_get() - Try to allocate a free bit from a &struct sbitmap. * @sb: Bitmap to allocate from. * @alloc_hint: Hint for where to start searching for a free bit. diff --git a/lib/sbitmap.c b/lib/sbitmap.c index e6a9c06ec70c..563ae9d75fb8 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -327,7 +327,8 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, } EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); -void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) +static void sbitmap_queue_update_batch_wake(struct sbitmap_queue *sbq, + unsigned int depth) { unsigned int wake_batch = sbq_calc_wake_batch(depth); int i; @@ -342,6 +343,11 @@ void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) for (i = 0; i < SBQ_WAIT_QUEUES; i++) atomic_set(&sbq->ws[i].wait_cnt, 1); } +} + +void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth) +{ + sbitmap_queue_update_batch_wake(sbq, depth); sbitmap_resize(&sbq->sb, depth); } EXPORT_SYMBOL_GPL(sbitmap_queue_resize); @@ -403,6 +409,15 @@ int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq, } EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow); +/* + * User has limited the shallow depth to 'depth', update batch wake counts + */ +void sbitmap_queue_shallow_depth(struct sbitmap_queue *sbq, unsigned int depth) +{ + sbitmap_queue_update_batch_wake(sbq, depth); +} +EXPORT_SYMBOL_GPL(sbitmap_queue_shallow_depth); + static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq) { int i, wake_index; -- 2.7.4
