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+

3 files changed, 16 insertions, 15 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index ba44fdfda66b..9e1569107cd6 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1058,7 +1058,7 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
 
         for (;;) {
                 if (affd) {
-                        nvec = irq_calc_affinity_vectors(nvec, affd);
+                        nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
                         if (nvec < minvec)
                                 return -ENOSPC;
                 }
@@ -1097,7 +1097,7 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
 
         for (;;) {
                 if (affd) {
-                        nvec = irq_calc_affinity_vectors(nvec, affd);
+                        nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
                         if (nvec < minvec)
                                 return -ENOSPC;
                 }
@@ -1165,16 +1165,6 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
         if (flags & PCI_IRQ_AFFINITY) {
                 if (!affd)
                         affd = &msi_default_affd;
-
-                if (affd->pre_vectors + affd->post_vectors > min_vecs)
-                        return -EINVAL;
-
-                /*
-                 * If there aren't any vectors left after applying the pre/post
-                 * vectors don't bother with assigning affinity.
-                 */
-                if (affd->pre_vectors + affd->post_vectors == min_vecs)
-                        affd = NULL;
         } else {
                 if (WARN_ON(affd))
                         affd = NULL;
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index a6fba4804672..0991f973f8ca 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -291,7 +291,7 @@ extern int
 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
 
 struct cpumask *irq_create_affinity_masks(int nvec, const struct irq_affinity *affd);
-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);
 
 #else /* CONFIG_SMP */
 
@@ -331,7 +331,7 @@ irq_create_affinity_masks(int nvec, const struct irq_affinity *affd)
 }
 
 static inline int
-irq_calc_affinity_vectors(int maxvec, const struct irq_affinity *affd)
+irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd)
 {
         return maxvec;
 }
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);