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Date: Thu, 21 May 2020 12:18:00 -0700 From: Saravana Kannan <saravanak@...gle.com> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org> Cc: Saravana Kannan <saravanak@...gle.com>, linux-kernel@...r.kernel.org, John Stultz <john.stultz@...aro.org>, kernel-team@...roid.com Subject: [PATCH v3 3/3] driver core: Add waiting_for_supplier sysfs file for devices 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@...gle.com> --- .../sysfs-devices-waiting_for_supplier | 17 ++++++++++++ drivers/base/core.c | 26 +++++++++++++++++++ 2 files changed, 43 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices-waiting_for_supplier diff --git a/Documentation/ABI/testing/sysfs-devices-waiting_for_supplier b/Documentation/ABI/testing/sysfs-devices-waiting_for_supplier new file mode 100644 index 000000000000..59d073d20db6 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-waiting_for_supplier @@ -0,0 +1,17 @@ +What: /sys/devices/.../waiting_for_supplier +Date: May 2020 +Contact: Saravana Kannan <saravanak@...gle.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. diff --git a/drivers/base/core.c b/drivers/base/core.c index 81c8ef088d3a..dfd4e94ef790 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1033,6 +1033,22 @@ 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. @@ -1057,6 +1073,7 @@ 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(); @@ -2126,8 +2143,16 @@ 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: @@ -2145,6 +2170,7 @@ 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); -- 2.27.0.rc0.183.gde8f92d652-goog
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