[tip:irq/urgent] genirq/affinity: Use get/put_online_cpus around cpumask operations

From: tip-bot for Christoph Hellwig
Date: Mon Aug 22 2016 - 05:28:58 EST


Commit-ID: 3ee0ce2a54dff07d09440723594df89bc1a12e79
Gitweb: http://git.kernel.org/tip/3ee0ce2a54dff07d09440723594df89bc1a12e79
Author: Christoph Hellwig <hch@xxxxxx>
AuthorDate: Thu, 11 Aug 2016 07:06:45 -0700
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 22 Aug 2016 11:22:44 +0200

genirq/affinity: Use get/put_online_cpus around cpumask operations

Without locking out CPU mask operations we might end up with an inconsistent
view of the cpumask in the function.

Fixes: 5e385a6ef31f: "genirq: Add a helper to spread an affinity mask for MSI/MSI-X vectors"
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: http://lkml.kernel.org/r/1470924405-25728-1-git-send-email-hch@xxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
kernel/irq/affinity.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index f689593..32f6cfc 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -39,6 +39,7 @@ struct cpumask *irq_create_affinity_mask(unsigned int *nr_vecs)
return NULL;
}

+ get_online_cpus();
if (max_vecs >= num_online_cpus()) {
cpumask_copy(affinity_mask, cpu_online_mask);
*nr_vecs = num_online_cpus();
@@ -56,6 +57,7 @@ struct cpumask *irq_create_affinity_mask(unsigned int *nr_vecs)
}
*nr_vecs = vecs;
}
+ put_online_cpus();

return affinity_mask;
}