diff options
author | Trond Myklebust <trond.myklebust@primarydata.com> | 2014-08-03 17:03:10 (GMT) |
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committer | J. Bruce Fields <bfields@redhat.com> | 2014-08-17 16:00:11 (GMT) |
commit | 983c684466e02b21f83c025ea539deee6c0aeac0 (patch) | |
tree | f55a16f3510ba10a78cd8cb757553ced2a38a639 /net/sunrpc/svc_xprt.c | |
parent | 106f359cf4d613ebf54cb9f29721bb956fc3460e (diff) | |
download | linux-983c684466e02b21f83c025ea539deee6c0aeac0.tar.xz |
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>
Diffstat (limited to 'net/sunrpc/svc_xprt.c')
-rw-r--r-- | net/sunrpc/svc_xprt.c | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 08e49d1..faaf2b4 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -348,8 +348,6 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) cpu = get_cpu(); pool = svc_pool_for_cpu(xprt->xpt_server, cpu); - put_cpu(); - spin_lock_bh(&pool->sp_lock); if (!list_empty(&pool->sp_threads) && @@ -382,10 +380,15 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) printk(KERN_ERR "svc_xprt_enqueue: server %p, rq_xprt=%p!\n", rqstp, rqstp->rq_xprt); - rqstp->rq_xprt = xprt; + /* Note the order of the following 3 lines: + * We want to assign xprt to rqstp->rq_xprt only _after_ + * we've woken up the process, so that we don't race with + * the lockless check in svc_get_next_xprt(). + */ svc_xprt_get(xprt); + wake_up_process(rqstp->rq_task); + rqstp->rq_xprt = xprt; pool->sp_stats.threads_woken++; - wake_up(&rqstp->rq_wait); } else { dprintk("svc: transport %p put into queue\n", xprt); list_add_tail(&xprt->xpt_ready, &pool->sp_sockets); @@ -394,6 +397,7 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) out_unlock: spin_unlock_bh(&pool->sp_lock); + put_cpu(); } /* @@ -509,7 +513,7 @@ void svc_wake_up(struct svc_serv *serv) svc_thread_dequeue(pool, rqstp); rqstp->rq_xprt = NULL; */ - wake_up(&rqstp->rq_wait); + wake_up_process(rqstp->rq_task); } else pool->sp_task_pending = 1; spin_unlock_bh(&pool->sp_lock); @@ -628,7 +632,6 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) { struct svc_xprt *xprt; struct svc_pool *pool = rqstp->rq_pool; - DECLARE_WAITQUEUE(wait, current); long time_left; /* Normally we will wait up to 5 seconds for any required @@ -654,15 +657,15 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) xprt = ERR_PTR(-EAGAIN); goto out; } - /* No data pending. Go to sleep */ - svc_thread_enqueue(pool, rqstp); - /* * We have to be able to interrupt this wait * to bring down the daemons ... */ set_current_state(TASK_INTERRUPTIBLE); + /* No data pending. Go to sleep */ + svc_thread_enqueue(pool, rqstp); + /* * checking kthread_should_stop() here allows us to avoid * locking and signalling when stopping kthreads that call @@ -676,14 +679,13 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) goto out; } - add_wait_queue(&rqstp->rq_wait, &wait); spin_unlock_bh(&pool->sp_lock); time_left = schedule_timeout(timeout); + __set_current_state(TASK_RUNNING); try_to_freeze(); - remove_wait_queue(&rqstp->rq_wait, &wait); xprt = rqstp->rq_xprt; if (xprt != NULL) return xprt; @@ -786,10 +788,10 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) printk(KERN_ERR "svc_recv: service %p, transport not NULL!\n", rqstp); - if (waitqueue_active(&rqstp->rq_wait)) - printk(KERN_ERR - "svc_recv: service %p, wait queue active!\n", - rqstp); + + /* Make sure the task pointer is set! */ + if (WARN_ON_ONCE(!rqstp->rq_task)) + rqstp->rq_task = current_task; err = svc_alloc_arg(rqstp); if (err) |