From 3d1cf435e201d1fd63e4346b141881aed086effd Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 15 Jan 2021 19:30:51 +0100 Subject: driver core: Extend device_is_dependent() If the device passed as the target (second argument) to device_is_dependent() is not completely registered (that is, it has been initialized, but not added yet), but the parent pointer of it is set, it may be missing from the list of the parent's children and device_for_each_child() called by device_is_dependent() cannot be relied on to catch that dependency. For this reason, modify device_is_dependent() to check the ancestors of the target device by following its parent pointer in addition to the device_for_each_child() walk. Fixes: 9ed9895370ae ("driver core: Functional dependencies tracking support") Reported-by: Stephan Gerhold Tested-by: Stephan Gerhold Reviewed-by: Saravana Kannan Signed-off-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/17705994.d592GUb2YH@kreacher Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'drivers/base/core.c') diff --git a/drivers/base/core.c b/drivers/base/core.c index 25e08e5f40bd..3819fd012e27 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -208,6 +208,16 @@ int device_links_read_lock_held(void) #endif #endif /* !CONFIG_SRCU */ +static bool device_is_ancestor(struct device *dev, struct device *target) +{ + while (target->parent) { + target = target->parent; + if (dev == target) + return true; + } + return false; +} + /** * device_is_dependent - Check if one device depends on another one * @dev: Device to check dependencies for. @@ -221,7 +231,12 @@ int device_is_dependent(struct device *dev, void *target) struct device_link *link; int ret; - if (dev == target) + /* + * The "ancestors" check is needed to catch the case when the target + * device has not been completely initialized yet and it is still + * missing from the list of children of its parent device. + */ + if (dev == target || device_is_ancestor(dev, target)) return 1; ret = device_for_each_child(dev, target, device_is_dependent); -- cgit v1.2.3 From e020ff611ba9be54e959e6b548038f8a020da1c9 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Sun, 10 Jan 2021 09:54:07 -0800 Subject: driver core: Fix device link device name collision The device link device's name was of the form: -- This can cause name collision as reported here [1] as device names are not globally unique. Since device names have to be unique within the bus/class, add the bus/class name as a prefix to the device names used to construct the device link device name. So the devuce link device's name will be of the form: :--: [1] - https://lore.kernel.org/lkml/20201229033440.32142-1-michael@walle.cc/ Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs") Cc: stable@vger.kernel.org Reported-by: Michael Walle Tested-by: Michael Walle Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210110175408.1465657-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-class-devlink | 4 ++-- Documentation/ABI/testing/sysfs-devices-consumer | 5 +++-- Documentation/ABI/testing/sysfs-devices-supplier | 5 +++-- drivers/base/core.c | 27 +++++++++++++----------- include/linux/device.h | 12 +++++++++++ 5 files changed, 35 insertions(+), 18 deletions(-) (limited to 'drivers/base/core.c') diff --git a/Documentation/ABI/testing/sysfs-class-devlink b/Documentation/ABI/testing/sysfs-class-devlink index b662f747c83e..8a21ce515f61 100644 --- a/Documentation/ABI/testing/sysfs-class-devlink +++ b/Documentation/ABI/testing/sysfs-class-devlink @@ -5,8 +5,8 @@ Description: Provide a place in sysfs for the device link objects in the kernel at any given time. The name of a device link directory, denoted as ... above, is of the form -- - where is the supplier device name and is - the consumer device name. + where is the supplier bus:device name and + is the consumer bus:device name. What: /sys/class/devlink/.../auto_remove_on Date: May 2020 diff --git a/Documentation/ABI/testing/sysfs-devices-consumer b/Documentation/ABI/testing/sysfs-devices-consumer index 1f06d74d1c3c..0809fda092e6 100644 --- a/Documentation/ABI/testing/sysfs-devices-consumer +++ b/Documentation/ABI/testing/sysfs-devices-consumer @@ -4,5 +4,6 @@ Contact: Saravana Kannan Description: The /sys/devices/.../consumer: are symlinks to device links where this device is the supplier. denotes the - name of the consumer in that device link. There can be zero or - more of these symlinks for a given device. + name of the consumer in that device link and is of the form + bus:device name. There can be zero or more of these symlinks + for a given device. diff --git a/Documentation/ABI/testing/sysfs-devices-supplier b/Documentation/ABI/testing/sysfs-devices-supplier index a919e0db5e90..207f5972e98d 100644 --- a/Documentation/ABI/testing/sysfs-devices-supplier +++ b/Documentation/ABI/testing/sysfs-devices-supplier @@ -4,5 +4,6 @@ Contact: Saravana Kannan Description: The /sys/devices/.../supplier: are symlinks to device links where this device is the consumer. denotes the - name of the supplier in that device link. There can be zero or - more of these symlinks for a given device. + name of the supplier in that device link and is of the form + bus:device name. There can be zero or more of these symlinks + for a given device. diff --git a/drivers/base/core.c b/drivers/base/core.c index 3819fd012e27..78f6db169d47 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -471,7 +471,9 @@ static int devlink_add_symlinks(struct device *dev, struct device *con = link->consumer; char *buf; - len = max(strlen(dev_name(sup)), strlen(dev_name(con))); + len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)), + strlen(dev_bus_name(con)) + strlen(dev_name(con))); + len += strlen(":"); len += strlen("supplier:") + 1; buf = kzalloc(len, GFP_KERNEL); if (!buf) @@ -485,12 +487,12 @@ static int devlink_add_symlinks(struct device *dev, if (ret) goto err_con; - snprintf(buf, len, "consumer:%s", dev_name(con)); + snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con)); ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf); if (ret) goto err_con_dev; - snprintf(buf, len, "supplier:%s", dev_name(sup)); + snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup)); ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf); if (ret) goto err_sup_dev; @@ -498,7 +500,7 @@ static int devlink_add_symlinks(struct device *dev, goto out; err_sup_dev: - snprintf(buf, len, "consumer:%s", dev_name(con)); + snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con)); sysfs_remove_link(&sup->kobj, buf); err_con_dev: sysfs_remove_link(&link->link_dev.kobj, "consumer"); @@ -521,7 +523,9 @@ static void devlink_remove_symlinks(struct device *dev, sysfs_remove_link(&link->link_dev.kobj, "consumer"); sysfs_remove_link(&link->link_dev.kobj, "supplier"); - len = max(strlen(dev_name(sup)), strlen(dev_name(con))); + len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)), + strlen(dev_bus_name(con)) + strlen(dev_name(con))); + len += strlen(":"); len += strlen("supplier:") + 1; buf = kzalloc(len, GFP_KERNEL); if (!buf) { @@ -529,9 +533,9 @@ static void devlink_remove_symlinks(struct device *dev, return; } - snprintf(buf, len, "supplier:%s", dev_name(sup)); + snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup)); sysfs_remove_link(&con->kobj, buf); - snprintf(buf, len, "consumer:%s", dev_name(con)); + snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con)); sysfs_remove_link(&sup->kobj, buf); kfree(buf); } @@ -752,8 +756,9 @@ struct device_link *device_link_add(struct device *consumer, link->link_dev.class = &devlink_class; device_set_pm_not_required(&link->link_dev); - dev_set_name(&link->link_dev, "%s--%s", - dev_name(supplier), dev_name(consumer)); + dev_set_name(&link->link_dev, "%s:%s--%s:%s", + dev_bus_name(supplier), dev_name(supplier), + dev_bus_name(consumer), dev_name(consumer)); if (device_register(&link->link_dev)) { put_device(consumer); put_device(supplier); @@ -1823,9 +1828,7 @@ const char *dev_driver_string(const struct device *dev) * never change once they are set, so they don't need special care. */ drv = READ_ONCE(dev->driver); - return drv ? drv->name : - (dev->bus ? dev->bus->name : - (dev->class ? dev->class->name : "")); + return drv ? drv->name : dev_bus_name(dev); } EXPORT_SYMBOL(dev_driver_string); diff --git a/include/linux/device.h b/include/linux/device.h index 89bb8b84173e..1779f90eeb4c 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -609,6 +609,18 @@ static inline const char *dev_name(const struct device *dev) return kobject_name(&dev->kobj); } +/** + * dev_bus_name - Return a device's bus/class name, if at all possible + * @dev: struct device to get the bus/class name of + * + * Will return the name of the bus/class the device is attached to. If it is + * not attached to a bus/class, an empty string will be returned. + */ +static inline const char *dev_bus_name(const struct device *dev) +{ + return dev->bus ? dev->bus->name : (dev->class ? dev->class->name : ""); +} + __printf(2, 3) int dev_set_name(struct device *dev, const char *name, ...); #ifdef CONFIG_NUMA -- cgit v1.2.3