4.4-stable review patch. If anyone has any objections, please let me know.
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From: Bart Van Assche bart.vanassche@wdc.com
commit 2afc9166f79b8f6da5f347f48515215ceee4ae37 upstream.
Introduce these two functions and export them such that the next patch can add calls to these functions from the SCSI core.
Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Acked-by: Tejun Heo tj@kernel.org Acked-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/sysfs/file.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/sysfs.h | 14 ++++++++++++++ 2 files changed, 58 insertions(+)
--- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -408,6 +408,50 @@ int sysfs_chmod_file(struct kobject *kob EXPORT_SYMBOL_GPL(sysfs_chmod_file);
/** + * sysfs_break_active_protection - break "active" protection + * @kobj: The kernel object @attr is associated with. + * @attr: The attribute to break the "active" protection for. + * + * With sysfs, just like kernfs, deletion of an attribute is postponed until + * all active .show() and .store() callbacks have finished unless this function + * is called. Hence this function is useful in methods that implement self + * deletion. + */ +struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr) +{ + struct kernfs_node *kn; + + kobject_get(kobj); + kn = kernfs_find_and_get(kobj->sd, attr->name); + if (kn) + kernfs_break_active_protection(kn); + return kn; +} +EXPORT_SYMBOL_GPL(sysfs_break_active_protection); + +/** + * sysfs_unbreak_active_protection - restore "active" protection + * @kn: Pointer returned by sysfs_break_active_protection(). + * + * Undo the effects of sysfs_break_active_protection(). Since this function + * calls kernfs_put() on the kernfs node that corresponds to the 'attr' + * argument passed to sysfs_break_active_protection() that attribute may have + * been removed between the sysfs_break_active_protection() and + * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after + * this function has returned. + */ +void sysfs_unbreak_active_protection(struct kernfs_node *kn) +{ + struct kobject *kobj = kn->parent->priv; + + kernfs_unbreak_active_protection(kn); + kernfs_put(kn); + kobject_put(kobj); +} +EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection); + +/** * sysfs_remove_file_ns - remove an object attribute with a custom ns tag * @kobj: object we're acting for * @attr: attribute descriptor --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -238,6 +238,9 @@ int __must_check sysfs_create_files(stru const struct attribute **attr); int __must_check sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr, umode_t mode); +struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr); +void sysfs_unbreak_active_protection(struct kernfs_node *kn); void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns); bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr); @@ -351,6 +354,17 @@ static inline int sysfs_chmod_file(struc return 0; }
+static inline struct kernfs_node * +sysfs_break_active_protection(struct kobject *kobj, + const struct attribute *attr) +{ + return NULL; +} + +static inline void sysfs_unbreak_active_protection(struct kernfs_node *kn) +{ +} + static inline void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns)