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Commit 09cf92b7 authored by Thomas Gleixner's avatar Thomas Gleixner
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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: default avatarThomas 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
parent cbb24dc7

arch/x86/kernel/irq.c

+6 −1
Original line number Diff line number Diff line
@@ -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);