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x86/irq: Retrieve irq data after locking irq_desc

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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
This commit is contained in:
Thomas Gleixner 2015-07-05 17:12:35 +00:00
parent cbb24dc761
commit 09cf92b784
1 changed files with 6 additions and 1 deletions
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7
arch/x86/kernel/irq.c
View file

@ -497,6 +497,11 @@ void fixup_irqs(void)
*/ */
mdelay(1); 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++) { for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
unsigned int irr; unsigned int irr;
@ -508,9 +513,9 @@ void fixup_irqs(void)
irq = __this_cpu_read(vector_irq[vector]); irq = __this_cpu_read(vector_irq[vector]);
desc = irq_to_desc(irq); desc = irq_to_desc(irq);
raw_spin_lock(&desc->lock);
data = irq_desc_get_irq_data(desc); data = irq_desc_get_irq_data(desc);
chip = irq_data_get_irq_chip(data); chip = irq_data_get_irq_chip(data);
raw_spin_lock(&desc->lock);
if (chip->irq_retrigger) { if (chip->irq_retrigger) {
chip->irq_retrigger(data); chip->irq_retrigger(data);
__this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED); __this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);