On 11/22/21 3:20 PM, Ming Lei wrote:
On Mon, Nov 22, 2021 at 09:53:53AM +0200, Sagi Grimberg wrote:
-static inline void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
- __releases(hctx->srcu)
+static inline void queue_unlock(struct request_queue *q, bool blocking,
+ int srcu_idx)
+ __releases(q->srcu)
{
- if (!(hctx->flags & BLK_MQ_F_BLOCKING))
+ if (!blocking)
rcu_read_unlock();
else
- srcu_read_unlock(hctx->queue->srcu, srcu_idx);
+ srcu_read_unlock(q->srcu, srcu_idx);
Maybe instead of passing blocking bool just look at srcu_idx?
if (srcu_idx < 0)
rcu_read_unlock();
else
srcu_read_unlock(q->srcu, srcu_idx);
This way needs to initialize srcu_idx in each callers.
Then look at q->has_srcu that Bart suggested?
Or look if the queue has srcu allocated?
if (!q->srcu)
rcu_read_unlock();
else
srcu_read_unlock(q->srcu, srcu_idx);
This way is worse since q->srcu may involve one new cacheline fetch.
hctx->flags is always hot, so it is basically zero cost to check it.
Yea, but the interface is awkward that the caller tells the
routine how it should lock/unlock...
