From fe59493240169a2cc3f445ae5f2a2308fda06b63 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 11 Sep 2017 14:29:15 +0200 Subject: [PATCH 1/2] PCI: Add dummy pci_acs_enabled() for CONFIG_PCI=n build If CONFIG_PCI=n and gcc (e.g. 4.1.2) decides not to inline get_pci_function_alias_group(), the build fails with: drivers/iommu/iommu.o: In function `get_pci_function_alias_group': iommu.c:(.text+0xfdc): undefined reference to `pci_acs_enabled' Due to the various dummies for PCI calls in the CONFIG_PCI=n case, pci_acs_enabled() never called, but not all versions of gcc are smart enough to realize that. While explicitly marking get_pci_function_alias_group() inline would fix the build, this would inflate the code for the CONFIG_PCI=y case, as get_pci_function_alias_group() is a not-so-small function called from two places. Hence fix the issue by introducing a dummy for pci_acs_enabled() instead. Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu") Signed-off-by: Geert Uytterhoeven Signed-off-by: Bjorn Helgaas Reviewed-by: Alex Williamson --- include/linux/pci.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index f68c58a93dd0..f4f8ee5a7362 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1685,6 +1685,8 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; } #define dev_is_pci(d) (false) #define dev_is_pf(d) (false) +static inline bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags) +{ return false; } #endif /* CONFIG_PCI */ /* Include architecture-dependent settings and functions */ From 9561475db680f7144d2223a409dd3d7e322aca03 Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Mon, 11 Sep 2017 09:45:40 +0200 Subject: [PATCH 2/2] PCI: Fix race condition with driver_override The driver_override implementation is susceptible to a race condition when different threads are reading vs. storing a different driver override. Add locking to avoid the race condition. This is in close analogy to commit 6265539776a0 ("driver core: platform: fix race condition with driver_override") from Adrian Salido. Fixes: 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override") Signed-off-by: Nicolai Stange Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org # v3.16+ --- drivers/pci/pci-sysfs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 1eecfa301f7f..8e075ea2743e 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -686,7 +686,7 @@ static ssize_t driver_override_store(struct device *dev, const char *buf, size_t count) { struct pci_dev *pdev = to_pci_dev(dev); - char *driver_override, *old = pdev->driver_override, *cp; + char *driver_override, *old, *cp; /* We need to keep extra room for a newline */ if (count >= (PAGE_SIZE - 1)) @@ -700,12 +700,15 @@ static ssize_t driver_override_store(struct device *dev, if (cp) *cp = '\0'; + device_lock(dev); + old = pdev->driver_override; if (strlen(driver_override)) { pdev->driver_override = driver_override; } else { kfree(driver_override); pdev->driver_override = NULL; } + device_unlock(dev); kfree(old); @@ -716,8 +719,12 @@ static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + ssize_t len; - return snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override); + device_lock(dev); + len = snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override); + device_unlock(dev); + return len; } static DEVICE_ATTR_RW(driver_override);