[PATCH V3 3/4] genirq/affinity: support to do irq vectors spread starting from any vector

[Ming Lei]

Now two parameters(start_vec, affv) are introduced to 
irq_build_affinity_masks(),
then this helper can build the affinity of each irq vector starting from
the irq vector of 'start_vec', and handle at most 'affv' vectors.

This way is required to do 2-stages irq vectors spread among all
possible CPUs.

Cc: Thomas Gleixner <t...@linutronix.de>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Ming Lei <ming....@redhat.com>
---
 kernel/irq/affinity.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index e119e86bed48..616f040c5d02 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -94,17 +94,17 @@ static int get_nodes_in_cpumask(cpumask_var_t 
*node_to_cpumask,
        return nodes;
 }
 
-static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
+static int irq_build_affinity_masks(const struct irq_affinity *affd,
+                                   int start_vec, int affv,
                                    cpumask_var_t *node_to_cpumask,
                                    const struct cpumask *cpu_mask,
                                    struct cpumask *nmsk,
                                    struct cpumask *masks)
 {
-       int affv = nvecs - affd->pre_vectors - affd->post_vectors;
        int last_affv = affv + affd->pre_vectors;
-       int curvec = affd->pre_vectors;
+       int curvec = start_vec;
        nodemask_t nodemsk = NODE_MASK_NONE;
-       int n, nodes, cpus_per_vec, extra_vecs;
+       int n, nodes, cpus_per_vec, extra_vecs, done = 0;
 
        nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
 
@@ -116,8 +116,10 @@ static int irq_build_affinity_masks(int nvecs, const 
struct irq_affinity *affd,
                for_each_node_mask(n, nodemsk) {
                        cpumask_copy(masks + curvec,
                                     node_to_cpumask[n]);
-                       if (++curvec == last_affv)
+                       if (++done == affv)
                                break;
+                       if (++curvec == last_affv)
+                               curvec = affd->pre_vectors;
                }
                goto out;
        }
@@ -150,13 +152,16 @@ static int irq_build_affinity_masks(int nvecs, const 
struct irq_affinity *affd,
                        irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
                }
 
-               if (curvec >= last_affv)
+               done += v;
+               if (done >= affv)
                        break;
+               if (curvec >= last_affv)
+                       curvec = affd->pre_vectors;
                --nodes;
        }
 
 out:
-       return curvec - affd->pre_vectors;
+       return done;
 }
 
 /**
@@ -169,6 +174,7 @@ static int irq_build_affinity_masks(int nvecs, const struct 
irq_affinity *affd,
 struct cpumask *
 irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 {
+       int affv = nvecs - affd->pre_vectors - affd->post_vectors;
        int curvec;
        struct cpumask *masks;
        cpumask_var_t nmsk, *node_to_cpumask;
@@ -198,7 +204,8 @@ irq_create_affinity_masks(int nvecs, const struct 
irq_affinity *affd)
        /* Stabilize the cpumasks */
        get_online_cpus();
        build_node_to_cpumask(node_to_cpumask);
-       curvec += irq_build_affinity_masks(nvecs, affd, node_to_cpumask,
+       curvec += irq_build_affinity_masks(affd, curvec, affv,
+                                          node_to_cpumask,
                                           cpu_possible_mask, nmsk, masks);
        put_online_cpus();
 
-- 
2.9.5