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Commit cbb24dc7 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/irq: Use proper locking in check_irq_vectors_for_cpu_disable() 



It's unsafe to examine fields in the irq descriptor w/o holding the
descriptor lock. Add proper locking.

While at it add a comment why the vector check can run lock less

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/20150705171102.236544164@linutronix.de
parent 5a3f75e3

arch/x86/kernel/irq.c

+12 −1
Original line number Diff line number Diff line
@@ -347,14 +347,22 @@ int check_irq_vectors_for_cpu_disable(void) 
			if (!desc)

				continue;



			/*

			 * Protect against concurrent action removal,

			 * affinity changes etc.

			 */

			raw_spin_lock(&desc->lock);

			data = irq_desc_get_irq_data(desc);

			cpumask_copy(&affinity_new, data->affinity);

			cpumask_clear_cpu(this_cpu, &affinity_new);



			/* Do not count inactive or per-cpu irqs. */

			if (!irq_has_action(irq) || irqd_is_per_cpu(data))

			if (!irq_has_action(irq) || irqd_is_per_cpu(data)) {

				raw_spin_unlock(&desc->lock);

				continue;

			}



			raw_spin_unlock(&desc->lock);

			/*

			 * A single irq may be mapped to multiple

			 * cpu's vector_irq[] (for example IOAPIC cluster
@@ -385,6 +393,9 @@ int check_irq_vectors_for_cpu_disable(void) 
		 * vector. If the vector is marked in the used vectors

		 * bitmap or an irq is assigned to it, we don't count

		 * it as available.

		 *

		 * As this is an inaccurate snapshot anyway, we can do

		 * this w/o holding vector_lock.

		 */

		for (vector = FIRST_EXTERNAL_VECTOR;

		     vector < first_system_vector; vector++) {