Messages in this thread Patch in this message | | | Date | Tue, 7 Jul 2015 02:57:55 -0700 | From | tip-bot for Thomas Gleixner <> | Subject | [tip:x86/urgent] x86/irq: Use proper locking in check_irq_vectors_for_cpu_disable() |
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Commit-ID: cbb24dc761d95fe39a7a122bb1b298e9604cae15 Gitweb: http://git.kernel.org/tip/cbb24dc761d95fe39a7a122bb1b298e9604cae15 Author: Thomas Gleixner <tglx@linutronix.de> AuthorDate: Sun, 5 Jul 2015 17:12:33 +0000 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Tue, 7 Jul 2015 11:54:04 +0200
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: 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/20150705171102.236544164@linutronix.de --- arch/x86/kernel/irq.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 88b36648..85ca76e 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -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++) {
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