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Subject[PATCH 4.12 063/196] PCI/MSI: Ignore affinity if pre/post vector count is more than min_vecs
Date
4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Hernandez <michael.hernandez@cavium.com>

commit 6f9a22bc5775d231ab8fbe2c2f3c88e45e3e7c28 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/pci/msi.c | 14 ++------------
include/linux/interrupt.h | 4 ++--
kernel/irq/affinity.c | 13 ++++++++++++-
3 files changed, 16 insertions(+), 15 deletions(-)

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1058,7 +1058,7 @@ static int __pci_enable_msi_range(struct

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(struc

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(struc
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;
--- 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, cons
}

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;
}
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -66,6 +66,13 @@ irq_create_affinity_masks(int nvecs, con
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);

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