Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...

[pandora-kernel.git] / lib / cpumask.c

diff --git a/lib/cpumask.c b/lib/cpumask.c
index b810b75..c101230 100644 (file)
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -164,3 +164,66 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask)
        memblock_free_early(__pa(mask), cpumask_size());
 }
 #endif
+
+/**
+ * cpumask_set_cpu_local_first - set i'th cpu with local numa cpu's first
+ *
+ * @i: index number
+ * @numa_node: local numa_node
+ * @dstp: cpumask with the relevant cpu bit set according to the policy
+ *
+ * This function sets the cpumask according to a numa aware policy.
+ * cpumask could be used as an affinity hint for the IRQ related to a
+ * queue. When the policy is to spread queues across cores - local cores
+ * first.
+ *
+ * Returns 0 on success, -ENOMEM for no memory, and -EAGAIN when failed to set
+ * the cpu bit and need to re-call the function.
+ */
+int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
+{
+       cpumask_var_t mask;
+       int cpu;
+       int ret = 0;
+
+       if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
+               return -ENOMEM;
+
+       i %= num_online_cpus();
+
+       if (!cpumask_of_node(numa_node)) {
+               /* Use all online cpu's for non numa aware system */
+               cpumask_copy(mask, cpu_online_mask);
+       } else {
+               int n;
+
+               cpumask_and(mask,
+                           cpumask_of_node(numa_node), cpu_online_mask);
+
+               n = cpumask_weight(mask);
+               if (i >= n) {
+                       i -= n;
+
+                       /* If index > number of local cpu's, mask out local
+                        * cpu's
+                        */
+                       cpumask_andnot(mask, cpu_online_mask, mask);
+               }
+       }
+
+       for_each_cpu(cpu, mask) {
+               if (--i < 0)
+                       goto out;
+       }
+
+       ret = -EAGAIN;
+
+out:
+       free_cpumask_var(mask);
+
+       if (!ret)
+               cpumask_set_cpu(cpu, dstp);
+
+       return ret;
+}
+EXPORT_SYMBOL(cpumask_set_cpu_local_first);