[tip: irq/msi] PCI/MSI: Unbreak pci_irq_get_affinity()

["tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>]

The following commit has been merged into the irq/msi branch of tip:

Commit-ID:     d558285413ea2f934ab90223ba908c30c5113aee
Gitweb:        https://git.kernel.org/tip/d558285413ea2f934ab90223ba908c30c5113aee
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Sat, 18 Dec 2021 11:25:14 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 18 Dec 2021 20:33:21 +01:00

PCI/MSI: Unbreak pci_irq_get_affinity()

The recent cleanup of pci_irq_get_affinity() broke the function for
PCI/MSI-X and indices > 0. Only the MSI descriptor for PCI/MSI has more
than one affinity mask which can be retrieved via the MSI index.

PCI/MSI-X has one descriptor per vector and each has a single affinity
mask.

Use index 0 when accessing the affinity mask in the MSI descriptor when
MSI-X is enabled.

Fixes: f48235900182 ("PCI/MSI: Simplify pci_irq_get_affinity()")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/87v8zm9pmd.ffs@tglx


---
 drivers/pci/msi/msi.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index 7180241..c19c7ca 100644
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -1100,7 +1100,7 @@ EXPORT_SYMBOL(pci_irq_vector);
  */
 const struct cpumask *pci_irq_get_affinity(struct pci_dev *dev, int nr)
 {
-	int irq = pci_irq_vector(dev, nr);
+	int idx, irq = pci_irq_vector(dev, nr);
 	struct msi_desc *desc;
 
 	if (WARN_ON_ONCE(irq <= 0))
@@ -1113,7 +1113,13 @@ const struct cpumask *pci_irq_get_affinity(struct pci_dev *dev, int nr)
 
 	if (WARN_ON_ONCE(!desc->affinity))
 		return NULL;
-	return &desc->affinity[nr].mask;
+
+	/*
+	 * MSI has a mask array in the descriptor.
+	 * MSI-X has a single mask.
+	 */
+	idx = dev->msi_enabled ? nr : 0;
+	return &desc->affinity[idx].mask;
 }
 EXPORT_SYMBOL(pci_irq_get_affinity);