diff options
author | Chuck Lever <chuck.lever@oracle.com> | 2023-07-10 19:42:00 +0300 |
---|---|---|
committer | Chuck Lever <chuck.lever@oracle.com> | 2023-08-30 00:45:22 +0300 |
commit | 850bac3ae4a636e9e6bb8de62fe697ac171cb221 (patch) | |
tree | 722d1f3c68cda3971e5d6d774985467b887df69b /net/sunrpc/svc_xprt.c | |
parent | 82e5d82a45741839bd9dcb6636cfcf67747a5af5 (diff) | |
download | linux-850bac3ae4a636e9e6bb8de62fe697ac171cb221.tar.xz |
SUNRPC: Deduplicate thread wake-up code
Refactor: Extract the loop that finds an idle service thread from
svc_xprt_enqueue() and svc_wake_up(). Both functions do just about
the same thing.
Note that svc_wake_up() currently does not hold the RCU read lock
while waking the target thread. It indeed should hold the lock, just
as svc_xprt_enqueue() does, to ensure the rqstp does not vanish
during the wake-up. This patch adds the RCU lock for svc_wake_up().
Note that shrinking the pool thread count is rare, and calls to
svc_wake_up() are also quite infrequent. In practice, this race is
very unlikely to be hit, so we are not marking the lock fix for
stable backport at this time.
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc/svc_xprt.c')
-rw-r--r-- | net/sunrpc/svc_xprt.c | 44 |
1 files changed, 8 insertions, 36 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index cdea4b49cbc5..20c66f659113 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -457,7 +457,6 @@ static bool svc_xprt_ready(struct svc_xprt *xprt) void svc_xprt_enqueue(struct svc_xprt *xprt) { struct svc_pool *pool; - struct svc_rqst *rqstp = NULL; if (!svc_xprt_ready(xprt)) return; @@ -477,20 +476,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) list_add_tail(&xprt->xpt_ready, &pool->sp_sockets); spin_unlock_bh(&pool->sp_lock); - /* find a thread for this xprt */ - rcu_read_lock(); - list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) { - if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) - continue; - percpu_counter_inc(&pool->sp_threads_woken); - rqstp->rq_qtime = ktime_get(); - wake_up_process(rqstp->rq_task); - goto out_unlock; - } - set_bit(SP_CONGESTED, &pool->sp_flags); - rqstp = NULL; -out_unlock: - rcu_read_unlock(); + svc_pool_wake_idle_thread(pool); } EXPORT_SYMBOL_GPL(svc_xprt_enqueue); @@ -581,7 +567,10 @@ static void svc_xprt_release(struct svc_rqst *rqstp) svc_xprt_put(xprt); } -/* +/** + * svc_wake_up - Wake up a service thread for non-transport work + * @serv: RPC service + * * Some svc_serv's will have occasional work to do, even when a xprt is not * waiting to be serviced. This function is there to "kick" a task in one of * those services so that it can wake up and do that work. Note that we only @@ -590,27 +579,10 @@ static void svc_xprt_release(struct svc_rqst *rqstp) */ void svc_wake_up(struct svc_serv *serv) { - struct svc_rqst *rqstp; - struct svc_pool *pool; - - pool = &serv->sv_pools[0]; - - rcu_read_lock(); - list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) { - /* skip any that aren't queued */ - if (test_bit(RQ_BUSY, &rqstp->rq_flags)) - continue; - rcu_read_unlock(); - wake_up_process(rqstp->rq_task); - trace_svc_wake_up(rqstp->rq_task->pid); - return; - } - rcu_read_unlock(); + struct svc_pool *pool = &serv->sv_pools[0]; - /* No free entries available */ - set_bit(SP_TASK_PENDING, &pool->sp_flags); - smp_wmb(); - trace_svc_wake_up(0); + if (!svc_pool_wake_idle_thread(pool)) + set_bit(SP_TASK_PENDING, &pool->sp_flags); } EXPORT_SYMBOL_GPL(svc_wake_up); |