6.12-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai tiwai@suse.de
[ 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@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+ Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/devres.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c index 70f1a46d07c5e..643f85849ef64 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;