From 50fd4407b8bfbde7c1a0bfe4f24de7df37164342 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 27 Mar 2008 17:42:50 -0700 Subject: [PATCH] [NET]: Use local_irq_{save,restore}() in napi_complete(). Based upon a lockdep report. Since ->poll() can be invoked from netpoll with interrupts disabled, we must not unconditionally enable interrupts in napi_complete(). Instead we must use local_irq_{save,restore}(). Noticed by Peter Zijlstra: netpoll_poll() poll_napi() spin_trylock(&napi->poll_lock) poll_one_napi() napi->poll() := sky2_poll() napi_complete() local_irq_disable() local_irq_enable() <--- *BUG* irq_exit() do_softirq() net_rx_action() spin_lock(&napi->poll_lock) <--- Deadlock! Because we still hold the lock.... Signed-off-by: David S. Miller --- include/linux/netdevice.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index a2f003239c8..fae6a7ececd 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -383,9 +383,11 @@ static inline void __napi_complete(struct napi_struct *n) static inline void napi_complete(struct napi_struct *n) { - local_irq_disable(); + unsigned long flags; + + local_irq_save(flags); __napi_complete(n); - local_irq_enable(); + local_irq_restore(flags); } /** -- 2.20.1