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driver core: Add waiting_for_supplier sysfs file for devices

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This would be useful to check if a device is not probing because it's
waiting for a supplier to be added and then linked to before it can
probe.

To reduce sysfs clutter, this file is added only if it can ever be 1.
So, if fw_devlink is disabled or set to permissive, this file is not
added. Also, this file is removed once the device probes as it's no
longer relevant.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200521191800.136035-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Saravana Kannan 2020-05-21 12:18:00 -07:00 committed by Greg Kroah-Hartman
parent 8fd456ec0c
commit da6d647598
2 changed files with 43 additions and 0 deletions
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17
Documentation/ABI/testing/sysfs-devices-waiting_for_supplier Normal file
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@ -0,0 +1,17 @@
What: /sys/devices/.../waiting_for_supplier
Date: May 2020
Contact: Saravana Kannan <saravanak@google.com>
Description:
The /sys/devices/.../waiting_for_supplier attribute is only
present when fw_devlink kernel command line option is enabled
and is set to something stricter than "permissive". It is
removed once a device probes successfully (because the
information is no longer relevant). The number read from it (0
or 1) reflects whether the device is waiting for one or more
suppliers to be added and then linked to using device links
before the device can probe.
A value of 0 means the device is not waiting for any suppliers
to be added before it can probe. A value of 1 means the device
is waiting for one or more suppliers to be added before it can
probe.

26
drivers/base/core.c
View File

@ -1041,6 +1041,22 @@ static void device_link_drop_managed(struct device_link *link)
kref_put(&link->kref, __device_link_del);
}
static ssize_t waiting_for_supplier_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
bool val;
device_lock(dev);
mutex_lock(&wfs_lock);
val = !list_empty(&dev->links.needs_suppliers)
&& dev->links.need_for_probe;
mutex_unlock(&wfs_lock);
device_unlock(dev);
return sprintf(buf, "%u\n", val);
}
static DEVICE_ATTR_RO(waiting_for_supplier);
/**
* device_links_driver_bound - Update device links after probing its driver.
* @dev: Device to update the links for.
@ -1065,6 +1081,7 @@ void device_links_driver_bound(struct device *dev)
mutex_lock(&wfs_lock);
list_del_init(&dev->links.needs_suppliers);
mutex_unlock(&wfs_lock);
device_remove_file(dev, &dev_attr_waiting_for_supplier);
device_links_write_lock();
@ -2144,8 +2161,16 @@ static int device_add_attrs(struct device *dev)
goto err_remove_dev_groups;
}
if (fw_devlink_flags && !fw_devlink_is_permissive()) {
error = device_create_file(dev, &dev_attr_waiting_for_supplier);
if (error)
goto err_remove_dev_online;
}
return 0;
err_remove_dev_online:
device_remove_file(dev, &dev_attr_online);
err_remove_dev_groups:
device_remove_groups(dev, dev->groups);
err_remove_type_groups:
@ -2163,6 +2188,7 @@ static void device_remove_attrs(struct device *dev)
struct class *class = dev->class;
const struct device_type *type = dev->type;
device_remove_file(dev, &dev_attr_waiting_for_supplier);
device_remove_file(dev, &dev_attr_online);
device_remove_groups(dev, dev->groups);