The patch below does not apply to the 6.13-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.13.y git checkout FETCH_HEAD git cherry-pick -x d555ed45a5a10a813528c7685f432369d536ae3d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025021021-recast-wrinkly-f4a0@gregkh' --subject-prefix 'PATCH 6.13.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d555ed45a5a10a813528c7685f432369d536ae3d Mon Sep 17 00:00:00 2001 From: Takashi Iwai tiwai@suse.de Date: Thu, 31 Oct 2024 14:42:56 +0100 Subject: [PATCH] PCI: Restore original INTX_DISABLE bit by pcim_intx()
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@suse.de Fixes: 25216afc9db5 ("PCI: Add managed pcim_intx()") Link: https://lore.kernel.org/87v7xk2ps5.wl-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Philipp Stanner pstanner@redhat.com Cc: stable@vger.kernel.org # v6.11+
diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c index d1d97a4bb36d..3431a7df3e0d 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; + u16 pci_command;
- res = devres_find(dev, pcim_intx_restore, NULL, NULL); - if (res) - return res; - - 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;