File 26063-x86-HPET-affinity-lock.patch of Package xen.openSUSE_12.1_Update

# HG changeset patch
# User Jan Beulich <jbeulich@suse.com>
# Date 1350476000 -7200
# Node ID 1f4be6ee4619c88c273cb457d8e7f1eee49d00dd
# Parent  ec8a091efcce717584b00ce76e3cec40a6247ebc
x86/HPET: obtain proper lock for changing IRQ affinity

The IRQ descriptor lock should be held while adjusting the affinity of
any IRQ; the HPET channel lock isn't sufficient to protect namely
against races with moving the IRQ to a different CPU.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -482,6 +482,16 @@ static struct hpet_event_channel *hpet_g
     return ch;
 }
 
+static void set_channel_irq_affinity(const struct hpet_event_channel *ch)
+{
+    struct irq_desc *desc = irq_to_desc(ch->irq);
+
+    ASSERT(!local_irq_is_enabled());
+    spin_lock(&desc->lock);
+    desc->handler->set_affinity(ch->irq, cpumask_of_cpu(ch->cpu));
+    spin_unlock(&desc->lock);
+}
+
 static void hpet_attach_channel(int cpu, struct hpet_event_channel *ch)
 {
     ASSERT(spin_is_locked(&ch->lock));
@@ -495,9 +505,7 @@ static void hpet_attach_channel(int cpu,
     if ( ch->cpu != cpu )
         return;
 
-    /* set irq affinity */
-    irq_desc[ch->irq].handler->
-        set_affinity(ch->irq, cpumask_of_cpu(ch->cpu));
+    set_channel_irq_affinity(ch);
 }
 
 static void hpet_detach_channel(int cpu, struct hpet_event_channel *ch)
@@ -518,9 +526,7 @@ static void hpet_detach_channel(int cpu,
     }
 
     ch->cpu = first_cpu(ch->cpumask);
-    /* set irq affinity */
-    irq_desc[ch->irq].handler->
-        set_affinity(ch->irq, cpumask_of_cpu(ch->cpu));
+    set_channel_irq_affinity(ch);
 }
 
 #include <asm/mc146818rtc.h>