Commit-ID: cbb24dc761d95fe39a7a122bb1b298e9604cae15
Gitweb: http://git.kernel.org/tip/cbb24dc761d95fe39a7a122bb1b298e9604cae15
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Sun, 5 Jul 2015 17:12:33 +0000
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: xiao jin <jin.xiao@xxxxxxxxx>
Cc: Joerg Roedel <jroedel@xxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Yanmin Zhang <yanmin_zhang@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150705171102.236544164@xxxxxxxxxxxxx
---
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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