[PATCH V3 5/5] genirq/affinity: Document .calc_sets as required in case of multiple sets

Ming Lei
2019-02-13T10:51:27Z

Now NVMe has implemented the .calc_sets callback for caculating each
set's vectors.

For other cases of multiple IRQ sets, pre-caculating each set's vectors
before allocating IRQ vectors can't work because the whole vectors
number is unknow at that time.

So document .calc_sets as required explicitly for multiple sets.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
drivers/pci/msi.c | 16 ++++++++++------
include/linux/interrupt.h | 3 ++-
2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 96978459e2a0..199d708b4099 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1036,10 +1036,12 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
return -ERANGE;

/*
- * If the caller is passing in sets, we can't support a range of
- * vectors. The caller needs to handle that.
+ * If the caller requests multiple sets of IRQs where each set
+ * requires different affinity, it must also supply a ->calc_sets()
+ * callback to compute vectors for each set after whole vectors are
+ * allocated.
*/
- if (affd && affd->nr_sets && minvec != maxvec)
+ if (affd && affd->nr_sets > 1 && !affd->calc_sets)
return -EINVAL;

if (WARN_ON_ONCE(dev->msi_enabled))
@@ -1094,10 +1096,12 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
return -ERANGE;

/*
- * If the caller is passing in sets, we can't support a range of
- * supported vectors. The caller needs to handle that.
+ * If the caller requests multiple sets of IRQs where each set
+ * requires different affinity, it must also supply a ->calc_sets()
+ * callback to compute vectors for each set after whole vectors are
+ * allocated.
*/
- if (affd && affd->nr_sets && minvec != maxvec)
+ if (affd && affd->nr_sets > 1 && !affd->calc_sets)
return -EINVAL;

if (WARN_ON_ONCE(dev->msix_enabled))
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 7a27f6ba1f2f..a053f7fb0ff1 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -269,7 +269,8 @@ 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
+ * @calc_sets: Callback for caculating set vectors, required for
+ * multiple irq sets.
* @priv: Private data of @calc_sets
*/
struct irq_affinity {
--
2.9.5