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sysctl: Comments to make the code clearer.

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Document get_subdir and that find_subdir alwasy takes a reference.

Suggested-by:  Lucian Adrian Grijincu <lucian.grijincu@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2012-01-30 21:23:52 -08:00
parent 0eb97f38d2
commit 60f126d93b
1 changed files with 16 additions and 0 deletions
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16
fs/proc/proc_sysctl.c
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@ -73,6 +73,7 @@ static int namecmp(const char *name1, int len1, const char *name2, int len2)
return cmp;
}
/* Called under sysctl_lock */
static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_dir *dir, const char *name, int namelen)
{
@ -864,6 +865,18 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
return new;
}
/**
* get_subdir - find or create a subdir with the specified name.
* @dir: Directory to create the subdirectory in
* @name: The name of the subdirectory to find or create
* @namelen: The length of name
*
* Takes a directory with an elevated reference count so we know that
* if we drop the lock the directory will not go away. Upon success
* the reference is moved from @dir to the returned subdirectory.
* Upon error an error code is returned and the reference on @dir is
* simply dropped.
*/
static struct ctl_dir *get_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
@ -885,12 +898,14 @@ static struct ctl_dir *get_subdir(struct ctl_dir *dir,
if (!new)
goto failed;
/* Was the subdir added while we dropped the lock? */
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
/* Nope. Use the our freshly made directory entry. */
err = insert_header(dir, &new->header);
subdir = ERR_PTR(err);
if (err)
@ -1190,6 +1205,7 @@ struct ctl_table_header *__register_sysctl_table(
spin_lock(&sysctl_lock);
dir = &set->dir;
/* Reference moved down the diretory tree get_subdir */
dir->header.nreg++;
spin_unlock(&sysctl_lock);