Subject: fix for BUG: using smp_processor_id() in preemptible code

Fixes using smp_processor_id() in preemptible code as seen when __qdisc_run
calls qdisc_restart which calls handle_dev_cpu_collision

This is fixed by disabling irqs (and preemption) around cpu_collision++
in handle_dev_cpu_collision

Signed-off-by: John Kacur <jkacur at gmail dot com>

Index: linux-2.6.26.1-rt1.jk/net/sched/sch_generic.c
===================================================================
--- linux-2.6.26.1-rt1.jk.orig/net/sched/sch_generic.c
+++ linux-2.6.26.1-rt1.jk/net/sched/sch_generic.c
@@ -94,6 +94,7 @@ static inline int handle_dev_cpu_collisi
 					   struct Qdisc *q)
 {
 	int ret;
+	unsigned long flags;
 
 	if (unlikely(dev->xmit_lock_owner == (void *)current)) {
 		/*
@@ -112,7 +113,9 @@ static inline int handle_dev_cpu_collisi
 		 * Another cpu is holding lock, requeue & delay xmits for
 		 * some time.
 		 */
+		local_irq_save(flags);
 		__get_cpu_var(netdev_rx_stat).cpu_collision++;
+		local_irq_restore(flags);
 		ret = dev_requeue_skb(skb, dev, q);
 	}