On Wed, Mar 01, 2017 at 03:31:58PM -0800, Himanshu Madhani wrote:
> From: Michael Hernandez <michael.hernandez@xxxxxxxxxx>
>
> 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.
>
> 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()
>
> Fixes: dfef358 ("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: Christoph Hellwig <hch@xxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> drivers/pci/msi.c | 25 ++++++++++++++++++-------
> 1 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 7f73bac..46c0cdd 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1091,6 +1091,15 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
>
> for (;;) {
> if (affd) {
> + /*
> + * 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 == nvec)
> + affd = NULL;
> + }
I don't really like this because affd->pre_vectors and
affd->post_vectors are not PCI MSI concepts. I think they really
belong in irq/affinity.c, e.g., maybe this could be checked in
irq_create_affinity_masks().
If that could be done, we wouldn't have to duplicate the checks here
for both MSI and MSI-X.
I raised a similar question earlier:
http://lkml.kernel.org/r/20170202173659.GD21267@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> + if (affd) {
> nvec = irq_calc_affinity_vectors(nvec, affd);
> if (nvec < minvec)
> return -ENOSPC;
> @@ -1138,6 +1147,15 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
>
> for (;;) {
> if (affd) {
> + /*
> + * 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 == nvec)
> + affd = NULL;
> + }
> + if (affd) {
> nvec = irq_calc_affinity_vectors(nvec, affd);
> if (nvec < minvec)
> return -ENOSPC;
> @@ -1209,13 +1227,6 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
>
> 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;
> --
> 1.7.1
>
