linux-kernel - [PATCH v2 1/2] PCI/MSI: Fix the confusing IRQ sysfs ABI for MSI-X

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Date:   Sat, 21 Aug 2021 10:37:43 +1200
From:   Barry Song <21cnbao@...il.com>
To:     21cnbao@...il.com, bhelgaas@...gle.com, corbet@....net
Cc:     Jonathan.Cameron@...wei.com, bilbao@...edu,
        gregkh@...uxfoundation.org, leon@...nel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linuxarm@...wei.com, luzmaximilian@...il.com,
        mchehab+huawei@...nel.org, schnelle@...ux.ibm.com,
        song.bao.hua@...ilicon.com
Subject: [PATCH v2 1/2] PCI/MSI: Fix the confusing IRQ sysfs ABI for MSI-X

From: Barry Song <song.bao.hua@...ilicon.com>

/sys/bus/pci/devices/.../irq sysfs ABI is very confusing at this
moment especially for MSI-X cases. While MSI sets IRQ to the first
number in the vector, MSI-X does nothing for this though it saves
default_irq in msix_setup_entries(). Weird the saved default_irq
for MSI-X is never used in pci_msix_shutdown(), which is quite
different with pci_msi_shutdown(). Thus, this patch moves to show
the first IRQ number which is from the first msi_entry for MSI-X.
Hopefully, this can make IRQ ABI more clear and more consistent.

Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Barry Song <song.bao.hua@...ilicon.com>
---
 drivers/pci/msi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 9232255..6bbf81b 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -771,6 +771,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	int ret;
 	u16 control;
 	void __iomem *base;
+	struct msi_desc *desc;
 
 	/* Ensure MSI-X is disabled while it is set up */
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
@@ -814,6 +815,10 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 
 	pcibios_free_irq(dev);
+
+	desc = first_pci_msi_entry(dev);
+	dev->irq = desc->irq;
+
 	return 0;
 
 out_avail:
@@ -1024,6 +1029,7 @@ static void pci_msix_shutdown(struct pci_dev *dev)
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
 	pci_intx_for_msi(dev, 1);
 	dev->msix_enabled = 0;
+	dev->irq = entry->msi_attrib.default_irq;
 	pcibios_alloc_irq(dev);
 }
 
-- 
1.8.3.1