From 605e644a5c9a8665b39d544354cfc4aafcefc694 Mon Sep 17 00:00:00 2001 From: Mojiong Qiu Date: Tue, 6 Nov 2012 16:08:15 +0800 Subject: [PATCH] xen/events: fix RCU warning, or Call idle notifier after irq_enter() commit 772aebcefeff310f80e32b874988af0076cb799d upstream. exit_idle() should be called after irq_enter(), otherwise it throws: [ INFO: suspicious RCU usage. ] 3.6.5 #1 Not tainted ------------------------------- include/linux/rcupdate.h:725 rcu_read_lock() used illegally while idle! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 1 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: (rcu_read_lock){......}, at: [] __atomic_notifier_call_chain+0x0/0x140 stack backtrace: Pid: 0, comm: swapper/0 Not tainted 3.6.5 #1 Call Trace: [] lockdep_rcu_suspicious+0xe2/0x130 [] __atomic_notifier_call_chain+0x12c/0x140 [] ? atomic_notifier_chain_unregister+0x90/0x90 [] ? trace_hardirqs_off+0xd/0x10 [] atomic_notifier_call_chain+0x16/0x20 [] exit_idle+0x43/0x50 [] xen_evtchn_do_upcall+0x25/0x50 [] xen_do_hypervisor_callback+0x1e/0x30 [] ? hypercall_page+0x3aa/0x1000 [] ? hypercall_page+0x3aa/0x1000 [] ? xen_safe_halt+0x10/0x20 [] ? default_idle+0xba/0x570 [] ? cpu_idle+0xdf/0x140 [] ? rest_init+0x135/0x144 [] ? csum_partial_copy_generic+0x16c/0x16c [] ? start_kernel+0x3db/0x3e8 [] ? repair_env_string+0x5a/0x5a [] ? x86_64_start_reservations+0x131/0x135 [] ? xen_start_kernel+0x465/0x46 Git commit 98ad1cc14a5c4fd658f9d72c6ba5c86dfd3ce0d5 Author: Frederic Weisbecker Date: Fri Oct 7 18:22:09 2011 +0200 x86: Call idle notifier after irq_enter() did this, but it missed the Xen code. Signed-off-by: Mojiong Qiu Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- drivers/xen/events.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/xen/events.c b/drivers/xen/events.c index 7595581d032c..99c53450b455 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -1374,8 +1374,8 @@ void xen_evtchn_do_upcall(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); - exit_idle(); irq_enter(); + exit_idle(); __xen_evtchn_do_upcall(); -- 2.39.5