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scsi: sysfs: Introduce sysfs_{un,}break_active_protection()

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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>
This commit is contained in:
Bart Van Assche 2018-08-02 10:51:40 -07:00 committed by Martin K. Petersen
parent 7fa8512330
commit 2afc9166f7
2 changed files with 58 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

44
fs/sysfs/file.c
View file

@ -405,6 +405,50 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
}
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

14
include/linux/sysfs.h
View file

@ -237,6 +237,9 @@ int __must_check sysfs_create_files(struct kobject *kobj,
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);
@ -350,6 +353,17 @@ static inline int sysfs_chmod_file(struct kobject *kobj,
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)