From 586095d339b1b46f4283863e6e8e15de662a3f93 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 10 May 2022 16:38:33 +0200 Subject: SUNRPC: Don't disable preemption while calling svc_pool_for_cpu(). svc_xprt_enqueue() disables preemption via get_cpu() and then asks for a pool of a specific CPU (current) via svc_pool_for_cpu(). While preemption is disabled, svc_xprt_enqueue() acquires svc_pool::sp_lock with bottom-halfs disabled, which can sleep on PREEMPT_RT. Disabling preemption is not required here. The pool is protected with a lock so the following list access is safe even cross-CPU. The following iteration through svc_pool::sp_all_threads is under RCU-readlock and remaining operations within the loop are atomic and do not rely on disabled-preemption. Use raw_smp_processor_id() as the argument for the requested CPU in svc_pool_for_cpu(). Reported-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Chuck Lever --- net/sunrpc/svc_xprt.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'net/sunrpc/svc_xprt.c') diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index f9d9922f1629..66cf720853bb 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -448,7 +448,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) { struct svc_pool *pool; struct svc_rqst *rqstp = NULL; - int cpu; if (!svc_xprt_ready(xprt)) return; @@ -461,8 +460,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) return; - cpu = get_cpu(); - pool = svc_pool_for_cpu(xprt->xpt_server, cpu); + pool = svc_pool_for_cpu(xprt->xpt_server, raw_smp_processor_id()); atomic_long_inc(&pool->sp_stats.packets); @@ -485,7 +483,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) rqstp = NULL; out_unlock: rcu_read_unlock(); - put_cpu(); trace_svc_xprt_enqueue(xprt, rqstp); } EXPORT_SYMBOL_GPL(svc_xprt_enqueue); -- cgit v1.2.3