This is a note to let you know that I've just added the patch titled
PCI: Restore original INTX_DISABLE bit by pcim_intx()
to the 6.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-restore-original-intx_disable-bit-by-pcim_intx.patch
and it can be found in the queue-6.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a2b38b54acdf05db9ad39f475292ffc647632b0e
Author: Takashi Iwai <tiwai@xxxxxxx>
Date: Thu Oct 31 14:42:56 2024 +0100
PCI: Restore original INTX_DISABLE bit by pcim_intx()
[ Upstream commit d555ed45a5a10a813528c7685f432369d536ae3d ]
pcim_intx() tries to restore the INTx bit at removal via devres, but there
is a chance that it restores a wrong value.
Because the value to be restored is blindly assumed to be the negative of
the enable argument, when a driver calls pcim_intx() unnecessarily for the
already enabled state, it'll restore to the disabled state in turn. That
is, the function assumes the case like:
// INTx == 1
pcim_intx(pdev, 0); // old INTx value assumed to be 1 -> correct
but it might be like the following, too:
// INTx == 0
pcim_intx(pdev, 0); // old INTx value assumed to be 1 -> wrong
Also, when a driver calls pcim_intx() multiple times with different enable
argument values, the last one will win no matter what value it is. This
can lead to inconsistency, e.g.
// INTx == 1
pcim_intx(pdev, 0); // OK
...
pcim_intx(pdev, 1); // now old INTx wrongly assumed to be 0
This patch addresses those inconsistencies by saving the original INTx
state at the first pcim_intx() call. For that, get_or_create_intx_devres()
is folded into pcim_intx() caller side; it allows us to simply check the
already allocated devres and record the original INTx along with the
devres_alloc() call.
Link: https://lore.kernel.org/r/20241031134300.10296-1-tiwai@xxxxxxx
Fixes: 25216afc9db5 ("PCI: Add managed pcim_intx()")
Link: https://lore.kernel.org/87v7xk2ps5.wl-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Philipp Stanner <pstanner@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v6.11+
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index cc31951347210..1adebcb263bd0 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -419,19 +419,12 @@ static void pcim_intx_restore(struct device *dev, void *data)
pci_intx(pdev, res->orig_intx);
}
-static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
+static void save_orig_intx(struct pci_dev *pdev, struct pcim_intx_devres *res)
{
- struct pcim_intx_devres *res;
-
- res = devres_find(dev, pcim_intx_restore, NULL, NULL);
- if (res)
- return res;
+ u16 pci_command;
- res = devres_alloc(pcim_intx_restore, sizeof(*res), GFP_KERNEL);
- if (res)
- devres_add(dev, res);
-
- return res;
+ pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+ res->orig_intx = !(pci_command & PCI_COMMAND_INTX_DISABLE);
}
/**
@@ -447,12 +440,23 @@ static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
int pcim_intx(struct pci_dev *pdev, int enable)
{
struct pcim_intx_devres *res;
+ struct device *dev = &pdev->dev;
- res = get_or_create_intx_devres(&pdev->dev);
- if (!res)
- return -ENOMEM;
+ /*
+ * pcim_intx() must only restore the INTx value that existed before the
+ * driver was loaded, i.e., before it called pcim_intx() for the
+ * first time.
+ */
+ res = devres_find(dev, pcim_intx_restore, NULL, NULL);
+ if (!res) {
+ res = devres_alloc(pcim_intx_restore, sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return -ENOMEM;
+
+ save_orig_intx(pdev, res);
+ devres_add(dev, res);
+ }
- res->orig_intx = !enable;
pci_intx(pdev, enable);
return 0;
