x86/irq: Retrieve irq data after locking irq_desc (09cf92b7) · Commits · 戴 / test

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

+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);

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