diff --git a/drivers/base/core.c b/drivers/base/core.c
index f191afe62b4d06633dc84490ec6e630d983c6a1a..ad0f4a2f25c466079c6c471f8b0f77a83b2845f0 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -407,6 +407,35 @@ void device_remove_bin_file(struct device *dev, struct bin_attribute *attr)
}
EXPORT_SYMBOL_GPL(device_remove_bin_file);
+/**
+ * device_schedule_callback - helper to schedule a callback for a device
+ * @dev: device.
+ * @func: callback function to invoke later.
+ *
+ * Attribute methods must not unregister themselves or their parent device
+ * (which would amount to the same thing). Attempts to do so will deadlock,
+ * since unregistration is mutually exclusive with driver callbacks.
+ *
+ * Instead methods can call this routine, which will attempt to allocate
+ * and schedule a workqueue request to call back @func with @dev as its
+ * argument in the workqueue's process context. @dev will be pinned until
+ * @func returns.
+ *
+ * Returns 0 if the request was submitted, -ENOMEM if storage could not
+ * be allocated.
+ *
+ * NOTE: This routine won't work if CONFIG_SYSFS isn't set! It uses an
+ * underlying sysfs routine (since it is intended for use by attribute
+ * methods), and if sysfs isn't available you'll get nothing but -ENOSYS.
+ */
+int device_schedule_callback(struct device *dev,
+ void (*func)(struct device *))
+{
+ return sysfs_schedule_callback(&dev->kobj,
+ (void (*)(void *)) func, dev);
+}
+EXPORT_SYMBOL_GPL(device_schedule_callback);
+
static void klist_children_get(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_parent);
diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index d48e3ca4752c444ba5d58d3c38abaa6a2daeeed9..5aeb68e732b024768dff52b0218b57fbfa106913 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -71,19 +71,31 @@ __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
* Provide an 'ungroup' attribute so the user can remove group devices no
* longer needed or accidentially created. Saves memory :)
*/
+static void ccwgroup_ungroup_callback(struct device *dev)
+{
+ struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
+
+ __ccwgroup_remove_symlinks(gdev);
+ device_unregister(dev);
+}
+
static ssize_t
ccwgroup_ungroup_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
struct ccwgroup_device *gdev;
+ int rc;
gdev = to_ccwgroupdev(dev);
if (gdev->state != CCWGROUP_OFFLINE)
return -EINVAL;
- __ccwgroup_remove_symlinks(gdev);
- device_unregister(dev);
-
+ /* Note that we cannot unregister the device from one of its
+ * attribute methods, so we have to use this roundabout approach.
+ */
+ rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
+ if (rc)
+ count = rc;
return count;
}
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index c275dcac3f18b7b4abc1bd984cb1601de3f0a770..939de0de18bc5d30e271fe864fbd0c962f1b4ef6 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -452,10 +452,22 @@ store_rescan_field (struct device *dev, struct device_attribute *attr, const cha
}
static DEVICE_ATTR(rescan, S_IWUSR, NULL, store_rescan_field);
+static void sdev_store_delete_callback(struct device *dev)
+{
+ scsi_remove_device(to_scsi_device(dev));
+}
+
static ssize_t sdev_store_delete(struct device *dev, struct device_attribute *attr, const char *buf,
size_t count)
{
- scsi_remove_device(to_scsi_device(dev));
+ int rc;
+
+ /* An attribute cannot be unregistered by one of its own methods,
+ * so we have to use this roundabout approach.
+ */
+ rc = device_schedule_callback(dev, sdev_store_delete_callback);
+ if (rc)
+ count = rc;
return count;
};
static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 8d4d839a9d887eb4a753da824e55a98542b26f21..1bafdf6e171cb5c73d9c0650368b2ad8795684e6 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -629,6 +629,60 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
}
EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);
+struct sysfs_schedule_callback_struct {
+ struct kobject *kobj;
+ void (*func)(void *);
+ void *data;
+ struct work_struct work;
+};
+
+static void sysfs_schedule_callback_work(struct work_struct *work)
+{
+ struct sysfs_schedule_callback_struct *ss = container_of(work,
+ struct sysfs_schedule_callback_struct, work);
+
+ (ss->func)(ss->data);
+ kobject_put(ss->kobj);
+ kfree(ss);
+}
+
+/**
+ * sysfs_schedule_callback - helper to schedule a callback for a kobject
+ * @kobj: object we're acting for.
+ * @func: callback function to invoke later.
+ * @data: argument to pass to @func.
+ *
+ * sysfs attribute methods must not unregister themselves or their parent
+ * kobject (which would amount to the same thing). Attempts to do so will
+ * deadlock, since unregistration is mutually exclusive with driver
+ * callbacks.
+ *
+ * Instead methods can call this routine, which will attempt to allocate
+ * and schedule a workqueue request to call back @func with @data as its
+ * argument in the workqueue's process context. @kobj will be pinned
+ * until @func returns.
+ *
+ * Returns 0 if the request was submitted, -ENOMEM if storage could not
+ * be allocated.
+ */
+int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
+ void *data)
+{
+ struct sysfs_schedule_callback_struct *ss;
+
+ ss = kmalloc(sizeof(*ss), GFP_KERNEL);
+ if (!ss)
+ return -ENOMEM;
+ kobject_get(kobj);
+ ss->kobj = kobj;
+ ss->func = func;
+ ss->data = data;
+ INIT_WORK(&ss->work, sysfs_schedule_callback_work);
+ schedule_work(&ss->work);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_schedule_callback);
+
EXPORT_SYMBOL_GPL(sysfs_create_file);
EXPORT_SYMBOL_GPL(sysfs_remove_file);
diff --git a/include/linux/device.h b/include/linux/device.h
index 39a3199a826db2726e60475195f64f03465c5acb..caad9bba965277f7abe77c25f234e7b3c3d07f3f 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -353,6 +353,8 @@ extern int __must_check device_create_bin_file(struct device *dev,
struct bin_attribute *attr);
extern void device_remove_bin_file(struct device *dev,
struct bin_attribute *attr);
+extern int device_schedule_callback(struct device *dev,
+ void (*func)(struct device *));
/* device resource management */
typedef void (*dr_release_t)(struct device *dev, void *res);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 523405e1e1f6463a5f8aa925655d97234adaefae..0544edda716888ee3ee26823be8cd82ac497c606 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -78,6 +78,9 @@ struct sysfs_ops {
#ifdef CONFIG_SYSFS
+extern int sysfs_schedule_callback(struct kobject *kobj,
+ void (*func)(void *), void *data);
+
extern int __must_check
sysfs_create_dir(struct kobject *, struct dentry *);
@@ -132,6 +135,12 @@ extern int __must_check sysfs_init(void);
#else /* CONFIG_SYSFS */
+static inline int sysfs_schedule_callback(struct kobject *kobj,
+ void (*func)(void *), void *data)
+{
+ return -ENOSYS;
+}
+
static inline int sysfs_create_dir(struct kobject * k, struct dentry *shadow)
{
return 0;