linux-kernel - Re: [BUG] using smp_processor_id() in preemptible as suspending

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Date:	Thu, 28 Feb 2008 00:11:48 +0100
From:	Karsten Wiese <fzu@...gehoertderstaat.de>
To:	"Dave Young" <hidave.darkstar@...il.com>
Cc:	paulmck@...ux.vnet.ibm.com,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, "Ingo Molnar" <mingo@...e.hu>
Subject: Re: [BUG] using smp_processor_id() in preemptible as suspending

Am Mittwoch, 27. Februar 2008 schrieb Dave Young:
> On Wed, Feb 27, 2008 at 3:45 AM, Paul E. McKenney
> <paulmck@...ux.vnet.ibm.com> wrote:
> > On Tue, Feb 26, 2008 at 08:33:54AM -0800, Andrew Morton wrote:
> >  > On Tue, 26 Feb 2008 16:24:11 +0800 Dave Young <hidave.darkstar@...il.com> wrote:
> >  >
> >  > > I don't know whom I should mail to, could you cc the proper guy? Thanks.
> >
> >  Hello, Dave,
> >
> >  Would you be willing to try out the following (untested, might not even
> >  compile) patch show at the very end of this message?  This assumes that
> >  you were running with CONFIG_PREEMPT_RCU, which seems most likely based
> >  on looking at your oops.
> 
> Built ok, but can't even resume now. (dark screen with cursor blinking
> on top-left of minitor)

Dave, can you give this untested patch a try?

thanks,
      Karsten

---
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index c7c5209..5a7f8fc 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -878,18 +878,20 @@ void rcu_offline_cpu(int cpu)
 	 * Otherwise rcu_barrier() will fail
 	 */
 
-	spin_lock_irqsave(&rdp->lock, flags);
+	local_irq_save(flags);
+
+	spin_lock(&rdp->lock);
 	rcu_offline_cpu_enqueue(rdp->donelist, rdp->donetail, list, tail);
 	for (i = GP_STAGES - 1; i >= 0; i--)
 		rcu_offline_cpu_enqueue(rdp->waitlist[i], rdp->waittail[i],
 						list, tail);
 	rcu_offline_cpu_enqueue(rdp->nextlist, rdp->nexttail, list, tail);
-	spin_unlock_irqrestore(&rdp->lock, flags);
+	spin_unlock(&rdp->lock);
 	rdp->waitlistcount = 0;
 
 	/* Disengage the newly dead CPU from the grace-period computation. */
 
-	spin_lock_irqsave(&rcu_ctrlblk.fliplock, flags);
+	spin_lock(&rcu_ctrlblk.fliplock);
 	rcu_check_mb(cpu);
 	if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) {
 		smp_mb();  /* Subsequent counter accesses must see new value */
@@ -906,7 +908,7 @@ void rcu_offline_cpu(int cpu)
 
 	cpu_clear(cpu, rcu_cpu_online_map);
 
-	spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, flags);
+	spin_unlock(&rcu_ctrlblk.fliplock);
 
 	/*
 	 * Place the removed callbacks on the current CPU's queue.
@@ -919,11 +921,13 @@ void rcu_offline_cpu(int cpu)
 	 */
 
 	rdp = RCU_DATA_ME();
-	spin_lock_irqsave(&rdp->lock, flags);
+	spin_lock(&rdp->lock);
 	*rdp->nexttail = list;
 	if (list)
 		rdp->nexttail = tail;
-	spin_unlock_irqrestore(&rdp->lock, flags);
+	spin_unlock(&rdp->lock);
+
+	local_irq_restore(flags);
 }
 
 void __devinit rcu_online_cpu(int cpu)
--
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