linux-kernel - [PATCH v3 2/2] PCI: avoid duplicate IDs in dynamic IDs list

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Message-Id: <20201117054409.3428-3-zhenzhong.duan@gmail.com>
Date:   Tue, 17 Nov 2020 13:44:09 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-pci@...r.kernel.org, bhelgaas@...gle.com, hch@...radead.org,
        alex.williamson@...hat.com, cohuck@...hat.com,
        Zhenzhong Duan <zhenzhong.duan@...il.com>
Subject: [PATCH v3 2/2] PCI: avoid duplicate IDs in dynamic IDs list

When a device ID data is writen to /sys/bus/pci/drivers/.../new_id,
only static ID table is checked for duplicate and multiple dynamic ID
entries of same kind are allowed to exist in a dynamic IDs list.

This doesn't cause user-visible broken behavior, but not user friendly.
remove_id_store() only remove one of the duplicate IDs, so if we add an
ID several times, we would have to remove it the same number of times
before it's completely gone.

Fix it by calling pci_match_device() which checks both dynamic and static
IDs to avoid inserting duplicate IDs in dynamic IDs list.

After fix, it shows below result which is expected:

echo "1af4 1041" > /sys/bus/pci/drivers/vfio-pci/new_id
echo "1af4 1041" > /sys/bus/pci/drivers/vfio-pci/new_id
-bash: echo: write error: File exists

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...il.com>
---
 drivers/pci/pci-driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index e928cfa..c4678d8 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -197,7 +197,7 @@ static ssize_t new_id_store(struct device_driver *driver, const char *buf,
 		pdev->subsystem_device = subdevice;
 		pdev->class = class;

-		if (pci_match_id(pdrv->id_table, pdev))
+		if (pci_match_device(pdrv, pdev))
 			retval = -EEXIST;

 		kfree(pdev);
-- 
1.8.3.1