linux-kernel - [tip: irq/urgent] PCI/MSI: Clarify usage of pci_msix_free

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Message-ID: <167696477130.387.8165200996017804708.tip-bot2@tip-bot2>
Date:   Tue, 21 Feb 2023 07:32:51 -0000
From:   "tip-bot2 for Reinette Chatre" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kevin Tian <kevin.tian@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, maz@...nel.org
Subject: [tip: irq/urgent] PCI/MSI: Clarify usage of pci_msix_free_irq()

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

Commit-ID:     e6cc6f175566dd21a3f6e384c24593b1c751dd74
Gitweb:        https://git.kernel.org/tip/e6cc6f175566dd21a3f6e384c24593b1c751dd74
Author:        Reinette Chatre <reinette.chatre@...el.com>
AuthorDate:    Tue, 14 Feb 2023 13:13:20 -08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 21 Feb 2023 08:25:14 +01:00

PCI/MSI: Clarify usage of pci_msix_free_irq()

pci_msix_free_irq() is used to free an interrupt on a PCI/MSI-X interrupt
domain.

The API description specifies that the interrupt to be freed was allocated
via pci_msix_alloc_irq_at().  This description limits the usage of
pci_msix_free_irq() since pci_msix_free_irq() can also be used to free
MSI-X interrupts allocated with, for example, pci_alloc_irq_vectors().

Remove the text stating that the interrupt to be freed had to be allocated
with pci_msix_alloc_irq_at(). The needed struct msi_map need not be from
pci_msix_alloc_irq_at() but can be created from scratch using
pci_irq_vector() to obtain the Linux IRQ number. Highlight that
pci_msix_free_irq() cannot be used to disable MSI-X to guide users that,
for example, pci_free_irq_vectors() remains to be needed.

Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Kevin Tian <kevin.tian@...el.com>
Link: https://lore.kernel.org/lkml/87r0xsd8j4.ffs@tglx
Link: https://lore.kernel.org/r/4c3e7a50d6e70f408812cd7ab199c6b4b326f9de.1676408572.git.reinette.chatre@intel.com
---
 drivers/pci/msi/api.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi/api.c b/drivers/pci/msi/api.c
index b8009aa..be679aa 100644
--- a/drivers/pci/msi/api.c
+++ b/drivers/pci/msi/api.c
@@ -163,11 +163,11 @@ EXPORT_SYMBOL_GPL(pci_msix_alloc_irq_at);

 /**
  * pci_msix_free_irq - Free an interrupt on a PCI/MSIX interrupt domain
- *		      which was allocated via pci_msix_alloc_irq_at()
  *
  * @dev:	The PCI device to operate on
  * @map:	A struct msi_map describing the interrupt to free
- *		as returned from the allocation function.
+ *
+ * Undo an interrupt vector allocation. Does not disable MSI-X.
  */
 void pci_msix_free_irq(struct pci_dev *dev, struct msi_map map)
 {