From 09cf92b784fae6109450c5d64f9908066d605249 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 5 Jul 2015 17:12:35 +0000
Subject: [PATCH] x86/irq: Retrieve irq data after locking irq_desc
irq_data is protected by irq_desc->lock, so retrieving the irq chip
from irq_data outside the lock is racy vs. an concurrent update. Move
it into the lock held region.
While at it add a comment why the vector walk does not require
vector_lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: xiao jin <jin.xiao@intel.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Link: http://lkml.kernel.org/r/20150705171102.331320612@linutronix.de
---
arch/x86/kernel/irq.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 85ca76e6241c..c7dfe1be784e 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -497,6 +497,11 @@ void fixup_irqs(void)
*/
mdelay(1);
+ /*
+ * We can walk the vector array of this cpu without holding
+ * vector_lock because the cpu is already marked !online, so
+ * nothing else will touch it.
+ */
for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
unsigned int irr;
@@ -508,9 +513,9 @@ void fixup_irqs(void)
irq = __this_cpu_read(vector_irq[vector]);
desc = irq_to_desc(irq);
+ raw_spin_lock(&desc->lock);
data = irq_desc_get_irq_data(desc);
chip = irq_data_get_irq_chip(data);
- raw_spin_lock(&desc->lock);
if (chip->irq_retrigger) {
chip->irq_retrigger(data);
__this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);
--
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