PCI/MSI: Ignore affinity if pre/post vector count is more than min_vecs

min_vecs is the minimum amount of vectors needed to operate in MSI-X mode
which may just include the vectors that don't need affinity.

Disabling affinity settings causes the qla2xxx driver scsi_add_host() to fail
when blk_mq is enabled as the blk_mq_pci_map_queues() expects affinity masks
on each vector.

Fixes: dfef358bd1be ("PCI/MSI: Don't apply affinity if there aren't enough vectors left")
Signed-off-by: Michael Hernandez <michael.hernandez@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org	# v4.10+

1 files changed, 12 insertions, 1 deletions

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index e2d356dd7581..9b71406d2eec 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -66,6 +66,13 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
         struct cpumask *masks;
         cpumask_var_t nmsk;
 
+        /*
+         * If there aren't any vectors left after applying the pre/post
+         * vectors don't bother with assigning affinity.
+         */
+        if (!affv)
+                return NULL;
+
         if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
                 return NULL;
 
@@ -140,15 +147,19 @@ out:
 
 /**
  * irq_calc_affinity_vectors - Calculate the optimal number of vectors
+ * @minvec:     The minimum number of vectors available
  * @maxvec:     The maximum number of vectors available
  * @affd:       Description of the affinity requirements
  */
-int irq_calc_affinity_vectors(int maxvec, const struct irq_affinity *affd)
+int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd)
 {
         int resv = affd->pre_vectors + affd->post_vectors;
         int vecs = maxvec - resv;
         int cpus;
 
+        if (resv > minvec)
+                return 0;
+
         /* Stabilize the cpumasks */
         get_online_cpus();
         cpus = cpumask_weight(cpu_online_mask);