1 files changed, 44 insertions, 18 deletions

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 278289c091bb..d737dc60ab52 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -230,6 +230,12 @@ static int irq_build_affinity_masks(const struct irq_affinity *affd,
         return ret;
 }
 
+static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
+{
+        affd->nr_sets = 1;
+        affd->set_size[0] = affvecs;
+}
+
 /**
  * irq_create_affinity_masks - Create affinity masks for multiqueue spreading
  * @nvecs:      The total number of vectors
@@ -240,20 +246,46 @@ static int irq_build_affinity_masks(const struct irq_affinity *affd,
 struct irq_affinity_desc *
 irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
 {
-        unsigned int affvecs, curvec, usedvecs, nr_sets, i;
-        unsigned int set_size[IRQ_AFFINITY_MAX_SETS];
+        unsigned int affvecs, curvec, usedvecs, i;
         struct irq_affinity_desc *masks = NULL;
 
         /*
-         * If there aren't any vectors left after applying the pre/post
-         * vectors don't bother with assigning affinity.
+         * Determine the number of vectors which need interrupt affinities
+         * assigned. If the pre/post request exhausts the available vectors
+         * then nothing to do here except for invoking the calc_sets()
+         * callback so the device driver can adjust to the situation. If there
+         * is only a single vector, then managing the queue is pointless as
+         * well.
          */
-        if (nvecs == affd->pre_vectors + affd->post_vectors)
-                return NULL;
+        if (nvecs > 1 && nvecs > affd->pre_vectors + affd->post_vectors)
+                affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
+        else
+                affvecs = 0;
+
+        /*
+         * Simple invocations do not provide a calc_sets() callback. Install
+         * the generic one. The check for affd->nr_sets is a temporary
+         * workaround and will be removed after the NVME driver is converted
+         * over.
+         */
+        if (!affd->nr_sets && !affd->calc_sets)
+                affd->calc_sets = default_calc_sets;
+
+        /*
+         * If the device driver provided a calc_sets() callback let it
+         * recalculate the number of sets and their size. The check will go
+         * away once the NVME driver is converted over.
+         */
+        if (affd->calc_sets)
+                affd->calc_sets(affd, affvecs);
 
         if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
                 return NULL;
 
+        /* Nothing to assign? */
+        if (!affvecs)
+                return NULL;
+
         masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
         if (!masks)
                 return NULL;
@@ -261,21 +293,13 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
         /* Fill out vectors at the beginning that don't need affinity */
         for (curvec = 0; curvec < affd->pre_vectors; curvec++)
                 cpumask_copy(&masks[curvec].mask, irq_default_affinity);
+
         /*
          * Spread on present CPUs starting from affd->pre_vectors. If we
          * have multiple sets, build each sets affinity mask separately.
          */
-        affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
-        nr_sets = affd->nr_sets;
-        if (!nr_sets) {
-                nr_sets = 1;
-                set_size[0] = affvecs;
-        } else {
-                memcpy(set_size, affd->set_size, nr_sets * sizeof(unsigned int));
-        }
-
-        for (i = 0, usedvecs = 0; i < nr_sets; i++) {
-                unsigned int this_vecs = set_size[i];
+        for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
+                unsigned int this_vecs = affd->set_size[i];
                 int ret;
 
                 ret = irq_build_affinity_masks(affd, curvec, this_vecs,
@@ -318,7 +342,9 @@ unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
         if (resv > minvec)
                 return 0;
 
-        if (affd->nr_sets) {
+        if (affd->calc_sets) {
+                set_vecs = maxvec - resv;
+        } else if (affd->nr_sets) {
                 unsigned int i;
 
                 for (i = 0, set_vecs = 0;  i < affd->nr_sets; i++)