Your summary is "Only disable affinity settings if pre and post vector
count is equal to max_vecs and not min_vecs", but the patch doesn't
mention max_vecs anywhere. There must be a clearer way to word this.
On Mon, Apr 17, 2017 at 06:19:25PM -0700, Himanshu Madhani wrote:
> 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@xxxxxxxxxx>
> Signed-off-by: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.10
> ---
> v4 --> v5
> o Fixed Zero day kernel build failure.
>
> v3 --> v4
> o Moved pre/post reserved vector range checks to affinity.c as per
> comments from Bjorn Helgaas.
>
> v2 --> v3
> o fixed code as per review comments.
>
> v1 --> v2
> o Moved the check from pci_alloc_irq_vectors_affinity() to
> __pci_enable_{msi|msix}_range()
>
>
> drivers/pci/msi.c | 14 ++------------
> include/linux/interrupt.h | 4 ++--
> kernel/irq/affinity.c | 12 +++++++++++-
> 3 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index d571bc330686..8adf22f41cf9 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1072,7 +1072,7 @@ 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;
> }
> @@ -1111,7 +1111,7 @@ 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;
> }
> @@ -1179,16 +1179,6 @@ 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 53144e78a369..63b246dd8258 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 d052947fe785..59645fa66385 100644
> --- a/kernel/irq/affinity.c
> +++ b/kernel/irq/affinity.c
> @@ -69,6 +69,13 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
> if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
> return NULL;
>
> + /*
> + * If there aren't any vectors left after applying the pre/post
> + * vectors don't bother with assigning affinity.
> + */
> + if (!affv)
> + return NULL;
This looks like it might require cleanup, e.g., branching to "out".
But the test of "affv" doesn't depend on the zalloc_cpu_mask_var(), so
you could just move this test above the call to zalloc_cpu_mask_var(),
and then you wouldn't need any cleanup.
> +
> masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
> if (!masks)
> goto out;
> @@ -143,12 +150,15 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
> * @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)
This function has a kernel-doc comment above it, and you're adding a
parameter, so please update the kernel-doc to match.
> {
> 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);
> --
> 2.12.0
>
