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driver core: Fix device link device name collision

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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/

Fixes: 287905e68d ("driver core: Expose device link details in sysfs")
Cc: stable@vger.kernel.org
Reported-by: Michael Walle <michael@walle.cc>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210110175408.1465657-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Saravana Kannan 2021-01-10 09:54:07 -08:00 committed by Greg Kroah-Hartman
parent 3d1cf435e2
commit e020ff611b
5 changed files with 35 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/ABI/testing/sysfs-class-devlink
View File

@ -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

5
Documentation/ABI/testing/sysfs-devices-consumer
View File

@ -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.

5
Documentation/ABI/testing/sysfs-devices-supplier
View File

@ -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.

27
drivers/base/core.c
View File

@ -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);

12
include/linux/device.h
View File

@ -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