SUNRPC: make rqst_should_sleep() idempotent()
Based on its name you would think that rqst_should_sleep() would be read-only, not changing anything. But in fact it will clear SP_TASK_PENDING if that was set. This is surprising, and it blurs the line between "check for work to do" and "dequeue work to do". So change the "test_and_clear" to simple "test" and clear the bit once the thread has decided to wake up and return to the caller. With this, it makes sense to *always* set SP_TASK_PENDING when asked, rather than to set it only if no thread could be woken up. [ cel: Previously TASK_PENDING indicated there is work waiting but no idle threads were found to pick up that work. After this patch, it acts as an XPT_BUSY flag for wake-ups that have no associated xprt. ] Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
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1 changed files with 5 additions and 3 deletions
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@ -581,8 +581,8 @@ void svc_wake_up(struct svc_serv *serv)
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{
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struct svc_pool *pool = &serv->sv_pools[0];
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if (!svc_pool_wake_idle_thread(pool))
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set_bit(SP_TASK_PENDING, &pool->sp_flags);
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set_bit(SP_TASK_PENDING, &pool->sp_flags);
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svc_pool_wake_idle_thread(pool);
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}
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EXPORT_SYMBOL_GPL(svc_wake_up);
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@ -704,7 +704,7 @@ rqst_should_sleep(struct svc_rqst *rqstp)
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struct svc_pool *pool = rqstp->rq_pool;
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/* did someone call svc_wake_up? */
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if (test_and_clear_bit(SP_TASK_PENDING, &pool->sp_flags))
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if (test_bit(SP_TASK_PENDING, &pool->sp_flags))
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return false;
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/* was a socket queued? */
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@ -748,6 +748,7 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp)
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set_bit(RQ_BUSY, &rqstp->rq_flags);
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smp_mb__after_atomic();
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clear_bit(SP_TASK_PENDING, &pool->sp_flags);
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rqstp->rq_xprt = svc_xprt_dequeue(pool);
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if (rqstp->rq_xprt)
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goto out_found;
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@ -756,6 +757,7 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp)
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return NULL;
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return NULL;
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out_found:
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clear_bit(SP_TASK_PENDING, &pool->sp_flags);
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/* Normally we will wait up to 5 seconds for any required
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* cache information to be provided.
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*/
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