[PATCH V2 2/4] genirq/affinity: add new callback for caculating set vectors

[Ming Lei <ming.lei@redhat.com>]

Currently pre-caculated set vectors are provided by driver for
allocating & spread vectors. This way only works when drivers passes
same 'max_vecs' and 'min_vecs' to pci_alloc_irq_vectors_affinity(),
also requires driver to retry the allocating & spread.

As Bjorn and Keith mentioned, the current usage & interface for irq sets
is a bit awkward because the retrying should have been avoided by providing
one resonable 'min_vecs'. However, if 'min_vecs' isn't same with
'max_vecs', number of the allocated vectors is unknown before calling
pci_alloc_irq_vectors_affinity(), then each set's vectors can't be
pre-caculated.

Add a new callback of .calc_sets into 'struct irq_affinity' so that
driver can caculate set vectors after IRQ vector is allocated and
before spread IRQ vectors. Add 'priv' so that driver may retrieve
its private data via the 'struct irq_affinity'.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 include/linux/interrupt.h |  4 ++++
 kernel/irq/affinity.c     | 13 +++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index a20150627a32..7a27f6ba1f2f 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -269,12 +269,16 @@ struct irq_affinity_notify {
  *			the MSI(-X) vector space
  * @nr_sets:		Length of passed in *sets array
  * @set_vectors:	Number of affinitized sets
+ * @calc_sets:		Callback for caculating set vectors
+ * @priv:		Private data of @calc_sets
  */
 struct irq_affinity {
 	int	pre_vectors;
 	int	post_vectors;
 	int	nr_sets;
 	int	set_vectors[IRQ_MAX_SETS];
+	void	(*calc_sets)(struct irq_affinity *, int nvecs);
+	void	*priv;
 };
 
 /**
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index a97b7c33d2db..34abba63df4d 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -264,11 +264,14 @@ irq_create_affinity_masks(int nvecs, struct irq_affinity *affd)
 	 * Spread on present CPUs starting from affd->pre_vectors. If we
 	 * have multiple sets, build each sets affinity mask separately.
 	 */
-	nr_sets = affd->nr_sets;
-	if (!nr_sets) {
+	if (affd->calc_sets) {
+		affd->calc_sets(affd, nvecs);
+		nr_sets = affd->nr_sets;
+	} else if (!affd->nr_sets) {
 		nr_sets = 1;
 		affd->set_vectors[0] = affvecs;
-	}
+	} else
+		nr_sets = affd->nr_sets;
 
 	for (i = 0, usedvecs = 0; i < nr_sets; i++) {
 		int this_vecs = affd->set_vectors[i];
@@ -314,7 +317,9 @@ int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity
 	if (resv > minvec)
 		return 0;
 
-	if (affd->nr_sets) {
+	if (affd->calc_sets) {
+		set_vecs = vecs;
+	} else if (affd->nr_sets) {
 		int i;
 
 		for (i = 0, set_vecs = 0;  i < affd->nr_sets; i++)
-- 
2.9.5