[PATCH] sysfs: add devm_sysfs_create_group() and friends

Dmitry Torokhov
2015-10-30T11:47:27Z

Many drivers create additional driver-specific device attributes when
binding to the device and providing managed version of sysfs_create_group()
will simplify unbinding and error handling in probe path for such drivers.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
fs/sysfs/group.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 10 ++++
2 files changed, 134 insertions(+)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 39a0199..9511437 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -13,6 +13,7 @@
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/dcache.h>
+#include <linux/device.h>
#include <linux/namei.h>
#include <linux/err.h>
#include "sysfs.h"
@@ -352,3 +353,126 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
}
}
EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
+
+struct sysfs_group_devres {
+ const struct attribute_group *group;
+};
+
+static int devm_sysfs_group_match(struct device *dev, void *res, void *data)
+{
+ return ((struct sysfs_group_devres *)res)->group == data;
+}
+
+static void devm_sysfs_group_remove_group(struct device *dev, void *res)
+{
+ struct sysfs_group_devres *devres = res;
+ const struct attribute_group *group = devres->group;
+
+ dev_dbg(dev, "%s: removing group %p\n", __func__, group);
+ sysfs_remove_group(&dev->kobj, group);
+}
+
+/**
+ * devm_sysfs_create_group - given a device, create a managed attribute group
+ * @dev: The device to create the group for
+ * @grp: The attribute group to create
+ *
+ * This function creates a group for the first time. It will explicitly
+ * warn and error if any of the attribute files being created already exist.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int devm_sysfs_create_group(struct device *dev,
+ const struct attribute_group *grp)
+{
+ struct sysfs_group_devres *devres;
+ int error;
+
+ devres = devres_alloc(devm_sysfs_group_remove_group,
+ sizeof(*devres), GFP_KERNEL);
+ if (!devres)
+ return -ENOMEM;
+
+ error = sysfs_create_group(&dev->kobj, grp);
+ if (error) {
+ devres_free(devres);
+ return error;
+ }
+
+ devres_add(dev, devres);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_sysfs_create_group);
+
+/**
+ * devm_sysfs_create_groups - create a bunch of managed attribute groups
+ * @dev: The device to create the group for
+ * @groups: The attribute groups to create, NULL terminated
+ *
+ * This function creates a bunch of managed attribute groups. If an error
+ * occurs when creating a group, all previously created groups will be
+ * removed, unwinding everything back to the original state when this
+ * function was called. It will explicitly warn and error if any of the
+ * attribute files being created already exist.
+ *
+ * Returns 0 on success or error code from sysfs_create_group on failure.
+ */
+int devm_sysfs_create_groups(struct device *dev,
+ const struct attribute_group **groups)
+{
+ int error;
+ int i;
+
+ if (!groups)
+ return 0;
+
+ for (i = 0; groups[i]; i++) {
+ error = devm_sysfs_create_group(dev, groups[i]);
+ if (error) {
+ while (--i >= 0)
+ devm_sysfs_remove_group(dev, groups[i]);
+ return error;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_sysfs_create_groups);
+
+/**
+ * devm_sysfs_remove_group: remove a managed group from a device
+ * @dev: device to remove the group from
+ * @grp: group to remove
+ *
+ * This function removes a group of attributes from a device. The attributes
+ * previously have to have been created for this group, otherwise it will fail.
+ */
+void devm_sysfs_remove_group(struct device *dev,
+ const struct attribute_group *grp)
+{
+ WARN_ON(devres_release(dev, devm_sysfs_group_remove_group,
+ devm_sysfs_group_match,
+ /* cast away const */ (void *)grp));
+}
+EXPORT_SYMBOL_GPL(devm_sysfs_remove_group);
+
+/**
+ * devm_sysfs_remove_groups - remove a list of managed groups
+ *
+ * @dev: The device for the groups to be removed from
+ * @groups: NULL terminated list of groups to be removed
+ *
+ * If groups is not NULL, remove the specified groups from the device.
+ */
+void devm_sysfs_remove_groups(struct device *dev,
+ const struct attribute_group **groups)
+{
+ int i;
+
+ if (!groups)
+ return;
+
+ for (i = 0; groups[i]; i++)
+ devm_sysfs_remove_group(dev, groups[i]);
+}
+EXPORT_SYMBOL_GPL(devm_sysfs_remove_groups);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 9f65758..b59a913 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -269,6 +269,16 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
const char *link_name);

+struct device;
+int __must_check devm_sysfs_create_group(struct device *dev,
+ const struct attribute_group *grp);
+int __must_check devm_sysfs_create_groups(struct device *dev,
+ const struct attribute_group **groups);
+void devm_sysfs_remove_group(struct device *dev,
+ const struct attribute_group *grp);
+void devm_sysfs_remove_groups(struct device *dev,
+ const struct attribute_group **groups);
+
void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);

int __must_check sysfs_init(void);
--
1.9.1

--
Dmitry