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authorTejun Heo <tj@kernel.org>2014-09-24 13:31:50 -0400
committerTejun Heo <tj@kernel.org>2014-09-24 13:31:50 -0400
commit2aad2a86f6685c10360ec8a5a55eb9ab7059cb72 (patch)
tree85da25f36ba0c8158becdc8ba940201652cf30ce /block
parentf47ad45784611297b699f3dffb6c7222b76afe64 (diff)
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percpu_ref: add PERCPU_REF_INIT_* flags
With the recent addition of percpu_ref_reinit(), percpu_ref now can be used as a persistent switch which can be turned on and off repeatedly where turning off maps to killing the ref and waiting for it to drain; however, there currently isn't a way to initialize a percpu_ref in its off (killed and drained) state, which can be inconvenient for certain persistent switch use cases. Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic selection of operation mode; however, currently a newly initialized percpu_ref is always in percpu mode making it impossible to avoid the latency overhead of switching to atomic mode. This patch adds @flags to percpu_ref_init() and implements the following flags. * PERCPU_REF_INIT_ATOMIC : start ref in atomic mode * PERCPU_REF_INIT_DEAD : start ref killed and drained These flags should be able to serve the above two use cases. v2: target_core_tpg.c conversion was missing. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 44a78ae3f899..d85fe01c44ef 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1796,7 +1796,7 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
goto err_hctxs;
if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
- GFP_KERNEL))
+ 0, GFP_KERNEL))
goto err_map;
setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);