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SUNRPC: get rid of the request wait queue
We're always _only_ waking up tasks from within the sp_threads list, so we know that they are enqueued and alive. The rq_wait waitqueue is just a distraction with extra atomic semantics. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
parent
106f359cf4
commit
983c684466
3 changed files with 17 additions and 18 deletions
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@ -280,7 +280,6 @@ struct svc_rqst {
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bool rq_splice_ok; /* turned off in gss privacy
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* to prevent encrypting page
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* cache pages */
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wait_queue_head_t rq_wait; /* synchronization */
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struct task_struct *rq_task; /* service thread */
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};
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@ -612,8 +612,6 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
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if (!rqstp)
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goto out_enomem;
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init_waitqueue_head(&rqstp->rq_wait);
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serv->sv_nrthreads++;
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spin_lock_bh(&pool->sp_lock);
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pool->sp_nrthreads++;
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@ -348,8 +348,6 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
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cpu = get_cpu();
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pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
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put_cpu();
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spin_lock_bh(&pool->sp_lock);
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if (!list_empty(&pool->sp_threads) &&
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@ -382,10 +380,15 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
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printk(KERN_ERR
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"svc_xprt_enqueue: server %p, rq_xprt=%p!\n",
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rqstp, rqstp->rq_xprt);
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rqstp->rq_xprt = xprt;
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/* Note the order of the following 3 lines:
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* We want to assign xprt to rqstp->rq_xprt only _after_
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* we've woken up the process, so that we don't race with
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* the lockless check in svc_get_next_xprt().
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*/
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svc_xprt_get(xprt);
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wake_up_process(rqstp->rq_task);
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rqstp->rq_xprt = xprt;
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pool->sp_stats.threads_woken++;
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wake_up(&rqstp->rq_wait);
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} else {
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dprintk("svc: transport %p put into queue\n", xprt);
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list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
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@ -394,6 +397,7 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
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out_unlock:
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spin_unlock_bh(&pool->sp_lock);
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put_cpu();
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}
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/*
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@ -509,7 +513,7 @@ void svc_wake_up(struct svc_serv *serv)
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svc_thread_dequeue(pool, rqstp);
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rqstp->rq_xprt = NULL;
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*/
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wake_up(&rqstp->rq_wait);
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wake_up_process(rqstp->rq_task);
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} else
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pool->sp_task_pending = 1;
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spin_unlock_bh(&pool->sp_lock);
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@ -628,7 +632,6 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
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{
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struct svc_xprt *xprt;
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struct svc_pool *pool = rqstp->rq_pool;
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DECLARE_WAITQUEUE(wait, current);
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long time_left;
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/* Normally we will wait up to 5 seconds for any required
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@ -654,15 +657,15 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
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xprt = ERR_PTR(-EAGAIN);
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goto out;
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}
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/* No data pending. Go to sleep */
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svc_thread_enqueue(pool, rqstp);
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/*
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* We have to be able to interrupt this wait
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* to bring down the daemons ...
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*/
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set_current_state(TASK_INTERRUPTIBLE);
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/* No data pending. Go to sleep */
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svc_thread_enqueue(pool, rqstp);
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/*
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* checking kthread_should_stop() here allows us to avoid
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* locking and signalling when stopping kthreads that call
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@ -676,14 +679,13 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
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goto out;
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}
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add_wait_queue(&rqstp->rq_wait, &wait);
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spin_unlock_bh(&pool->sp_lock);
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time_left = schedule_timeout(timeout);
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__set_current_state(TASK_RUNNING);
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try_to_freeze();
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remove_wait_queue(&rqstp->rq_wait, &wait);
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xprt = rqstp->rq_xprt;
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if (xprt != NULL)
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return xprt;
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@ -786,10 +788,10 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
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printk(KERN_ERR
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"svc_recv: service %p, transport not NULL!\n",
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rqstp);
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if (waitqueue_active(&rqstp->rq_wait))
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printk(KERN_ERR
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"svc_recv: service %p, wait queue active!\n",
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rqstp);
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/* Make sure the task pointer is set! */
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if (WARN_ON_ONCE(!rqstp->rq_task))
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rqstp->rq_task = current_task;
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err = svc_alloc_arg(rqstp);
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if (err)
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