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Groups > linux.kernel > #1284373

[PATCH tip/core/rcu 12/13] rcu: Move wakeup out from under rnp->lock

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From: Peter Zijlstra <peterz@infradead.org>

This patch removes a potential deadlock hazard by moving the
wake_up_process() in rcu_spawn_gp_kthread() out from under rnp->lock.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 40940b0d0310..87b604d0b0d2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4319,8 +4319,8 @@ static int __init rcu_spawn_gp_kthread(void)
 			sp.sched_priority = kthread_prio;
 			sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
 		}
-		wake_up_process(t);
 		raw_spin_unlock_irqrestore(&rnp->lock, flags);
+		wake_up_process(t);
 	}
 	rcu_spawn_nocb_kthreads();
 	rcu_spawn_boost_kthreads();
-- 
2.5.2

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[PATCH tip/core/rcu 0/10] Expedited-grace-period changes for 4.5 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:00 +0100
  [PATCH tip/core/rcu 09/13] rcu: Make cpu_needs_another_gp() be bool "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:10 +0100
  [PATCH tip/core/rcu 04/13] rcu: Remove lock-acquisition loop from rcu_read_unlock_special() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:10 +0100
  [PATCH tip/core/rcu 01/13] rcu: Move lock_class_key to local scope "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 02/13] kernel: Make rcu/tree_trace.c explicitly non-modular "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 03/13] rcu: Simplify rcu_sched_qs() control flow "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 06/13] rcu: Avoid tick_nohz_active checks on NOCBs CPUs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 07/13] rcu: Stop disabling interrupts in scheduler fastpaths "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 05/13] rcu: Fix obsolete rcu_bootup_announce_oddness() comment "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 12/13] rcu: Move wakeup out from under rnp->lock "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 11/13] rcu: Fix comment for rcu_dereference_raw_notrace "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 13/13] rcu: Make rcu_gp_init() be bool rather than int "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 08/13] rcu: Eliminate unused rcu_init_one() argument "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  [PATCH tip/core/rcu 10/13] rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-05 01:20 +0100
  Re: [PATCH tip/core/rcu 0/10] Expedited-grace-period changes for 4.5 Josh Triplett <josh@joshtriplett.org> - 2015-12-05 02:10 +0100
    Re: [PATCH tip/core/rcu 0/10] Expedited-grace-period changes for 4.5 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-12-06 03:30 +0100

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