[PATCH 2/5] genirq/affinity: allow driver to setup managed IRQ's affinity

Ming Lei
2019-01-25T09:54:22Z

This patch introduces callback of .setup_affinity into 'struct
irq_affinity', so that:

1) allow drivers to customize the affinity for managed IRQ, for
example, now NVMe has special requirement for read queues & poll
queues

2) 6da4b3ab9a6e9 ("genirq/affinity: Add support for allocating interrupt sets")
makes pci_alloc_irq_vectors_affinity() a bit difficult to use for
allocating interrupt sets: 'max_vecs' is required to same with 'min_vecs'.

With this patch, driver can implement their own .setup_affinity to
customize the affinity, then the above thing can be solved easily.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/interrupt.h | 26 +++++++++++++++++---------
kernel/irq/affinity.c | 6 ++++++
2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index c672f34235e7..f6cea778cf50 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -242,30 +242,38 @@ struct irq_affinity_notify {
};

/**
+ * struct irq_affinity_desc - Interrupt affinity descriptor
+ * @mask: cpumask to hold the affinity assignment
+ */
+struct irq_affinity_desc {
+ struct cpumask mask;
+ unsigned int is_managed : 1;
+};
+
+/**
* struct irq_affinity - Description for automatic irq affinity assignements
* @pre_vectors: Don't apply affinity to @pre_vectors at beginning of
* the MSI(-X) vector space
* @post_vectors: Don't apply affinity to @post_vectors at end of
* the MSI(-X) vector space
+ * @setup_affinity: Use driver's method to setup irq vectors affinity,
+ * and driver has to handle pre_vectors & post_vectors
+ * correctly, set 'is_managed' flag correct too
+ * @priv: Private data of @setup_affinity
* @nr_sets: Length of passed in *sets array
* @sets: Number of affinitized sets
*/
struct irq_affinity {
int pre_vectors;
int post_vectors;
+ int (*setup_affinity)(const struct irq_affinity *,
+ struct irq_affinity_desc *,
+ unsigned int);
+ void *priv;
int nr_sets;
int *sets;
};

-/**
- * struct irq_affinity_desc - Interrupt affinity descriptor
- * @mask: cpumask to hold the affinity assignment
- */
-struct irq_affinity_desc {
- struct cpumask mask;
- unsigned int is_managed : 1;
-};
-
#if defined(CONFIG_SMP)

extern cpumask_var_t irq_default_affinity;
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 118b66d64a53..7b77cbdf739c 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -257,6 +257,12 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
if (!masks)
return NULL;

+ if (affd->setup_affinity) {
+ if (affd->setup_affinity(affd, masks, nvecs))
+ return NULL;
+ return masks;
+ }
+
/* Fill out vectors at the beginning that don't need affinity */
for (curvec = 0; curvec < affd->pre_vectors; curvec++)
cpumask_copy(&masks[curvec].mask, irq_default_affinity);
--
2.9.5