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| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2022-05-10 16:38:33 +0200 |
|---|---|---|
| committer |   Chuck Lever <chuck.lever@oracle.com> | 2022-05-19 12:25:40 -0400 |
| commit | 586095d339b1b46f4283863e6e8e15de662a3f93 (patch) | |
| tree | 75c581d0e3e6e0141eddebd654f1ca3501c62195 | |
| parent | NFSD: Show state of courtesy client in client info (diff) | |
| download | linux-dev-586095d339b1b46f4283863e6e8e15de662a3f93.tar.xz linux-dev-586095d339b1b46f4283863e6e8e15de662a3f93.zip | |
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 <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 5 |
1 files changed, 1 insertions, 4 deletions
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); |