[tip:irq/core] genirq/affinity: Take reserved vectors into account when spreading irqs

[tip-bot for Christoph Hellwig]

Commit-ID:  bfe130773862bb3a02cdc4d4c2169f7f0210a46b
Gitweb:     http://git.kernel.org/tip/bfe130773862bb3a02cdc4d4c2169f7f0210a46b
Author:     Christoph Hellwig <hch@xxxxxx>
AuthorDate: Tue, 15 Nov 2016 10:12:58 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 16 Nov 2016 18:44:01 +0100

genirq/affinity: Take reserved vectors into account when spreading irqs

The recent addition of reserved vectors at the beginning or the end of the
vector space did not take the reserved vectors at the beginning into
account for the various loop exit conditions. As a consequence the last
vectors of the spread area are not included into the spread algorithm and
are treated like the reserved vectors at the end of the vector space and
get the default affinity mask assigned.

Sum up the affinity vectors and the reserved vectors at the beginning and
use the sum as exit condition.

[ tglx: Fixed all conditions instead of only one and massaged changelog ]

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: http://lkml.kernel.org/r/1479201178-29604-2-git-send-email-hch@xxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
 kernel/irq/affinity.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 17360bd..49eb38d 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -61,6 +61,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 {
 	int n, nodes, vecs_per_node, cpus_per_vec, extra_vecs, curvec;
 	int affv = nvecs - affd->pre_vectors - affd->post_vectors;
+	int last_affv = affv + affd->pre_vectors;
 	nodemask_t nodemsk = NODE_MASK_NONE;
 	struct cpumask *masks;
 	cpumask_var_t nmsk;
@@ -87,7 +88,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 	if (affv <= nodes) {
 		for_each_node_mask(n, nodemsk) {
 			cpumask_copy(masks + curvec, cpumask_of_node(n));
-			if (++curvec == affv)
+			if (++curvec == last_affv)
 				break;
 		}
 		goto done;
@@ -107,7 +108,8 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 		/* Calculate the number of cpus per vector */
 		ncpus = cpumask_weight(nmsk);
 
-		for (v = 0; curvec < affv && v < vecs_to_assign; curvec++, v++) {
+		for (v = 0; curvec < last_affv && v < vecs_to_assign;
+		     curvec++, v++) {
 			cpus_per_vec = ncpus / vecs_to_assign;
 
 			/* Account for extra vectors to compensate rounding errors */
@@ -119,7 +121,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
 			irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
 		}
 
-		if (curvec >= affv)
+		if (curvec >= last_affv)
 			break;
 	}