The device link device's name was of the form: <supplier-dev-name>--<consumer-dev-name>

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: <supplier-bus-name>:<supplier-dev-name>--<consumer-bus-name>:<consumer-dev-name>

[1] - https://lore.kernel.org/lkml/20201229033440.32142-1-michael@walle.cc/

Cc: stable@vger.kernel.org Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs") Reported-by: Michael Walle michael@walle.cc Signed-off-by: Saravana Kannan saravanak@google.com --- Documentation/ABI/testing/sysfs-class-devlink | 4 +-- .../ABI/testing/sysfs-devices-consumer | 5 ++-- .../ABI/testing/sysfs-devices-supplier | 5 ++-- drivers/base/core.c | 27 ++++++++++--------- include/linux/device.h | 12 +++++++++ 5 files changed, 35 insertions(+), 18 deletions(-)

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 <supplier>--<consumer> - where <supplier> is the supplier device name and <consumer> is - the consumer device name. + where <supplier> is the supplier bus:device name and <consumer> + 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 saravanak@google.com Description: The /sys/devices/.../consumer:<consumer> are symlinks to device links where this device is the supplier. <consumer> 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 saravanak@google.com Description: The /sys/devices/.../supplier:<supplier> are symlinks to device links where this device is the consumer. <supplier> 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 25e08e5f40bd..47a6faf1605a 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -456,7 +456,9 @@ 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) @@ -470,12 +472,12 @@ 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; @@ -483,7 +485,7 @@ 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"); @@ -506,7 +508,9 @@ 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) { @@ -514,9 +518,9 @@ 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); } @@ -737,8 +741,9 @@ 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); @@ -1808,9 +1813,7 @@ 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