genirq/affinity: Allow irq spreading from a given starting point

To support two stage irq vector spreading, it's required to add a starting
point to the spreading function. No functional change, just preparatory
work for the actual two stage change.

[ tglx: Renamed variables, tidied up the code and massaged changelog ]

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Link: https://lkml.kernel.org/r/20180308105358.1506-4-ming.lei@redhat.com

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index a9c3690..213695a 100644 (file)
--- 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 startvec, int numvecs,
                                    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 n, nodes, cpus_per_vec, extra_vecs, done = 0;
+       int last_affv = affd->pre_vectors + numvecs;
+       int curvec = startvec;
        nodemask_t nodemsk = NODE_MASK_NONE;
-       int n, nodes, cpus_per_vec, extra_vecs;
 
        nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
 
@@ -112,12 +112,13 @@ static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
         * If the number of nodes in the mask is greater than or equal the
         * number of vectors we just spread the vectors across the nodes.
         */
-       if (affv <= nodes) {
+       if (numvecs <= nodes) {
                for_each_node_mask(n, nodemsk) {
-                       cpumask_copy(masks + curvec,
-                                    node_to_cpumask[n]);
-                       if (++curvec == last_affv)
+                       cpumask_copy(masks + curvec, node_to_cpumask[n]);
+                       if (++done == numvecs)
                                break;
+                       if (++curvec == last_affv)
+                               curvec = affd->pre_vectors;
                }
                goto out;
        }
@@ -126,7 +127,7 @@ static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
                int ncpus, v, vecs_to_assign, vecs_per_node;
 
                /* Spread the vectors per node */
-               vecs_per_node = (affv - (curvec - affd->pre_vectors)) / nodes;
+               vecs_per_node = (numvecs - (curvec - affd->pre_vectors)) / nodes;
 
                /* Get the cpus on this node which are in the mask */
                cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
@@ -150,13 +151,16 @@ 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 >= numvecs)
                        break;
+               if (curvec >= last_affv)
+                       curvec = affd->pre_vectors;
                --nodes;
        }
 
 out:
-       return curvec - affd->pre_vectors;
+       return done;
 }
 
 /**
@@ -169,9 +173,9 @@ out:
 struct cpumask *
 irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 {
+       int curvec, affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
        cpumask_var_t nmsk, *node_to_cpumask;
        struct cpumask *masks = NULL;
-       int curvec;
 
        /*
         * If there aren't any vectors left after applying the pre/post
@@ -198,8 +202,9 @@ 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,
-                                          cpu_possible_mask, nmsk, masks);
+       curvec += irq_build_affinity_masks(affd, curvec, affvecs,
+                                          node_to_cpumask, cpu_possible_mask,
+                                          nmsk, masks);
        put_online_cpus();
 
        /* Fill out vectors at the end that don't need affinity */