diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2012-01-30 21:23:52 -0800 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-02-01 19:20:57 -0800 |
| commit | 60f126d93b210ae708e2a5bb4a3be2121831f2a0 (patch) | |
| tree | 1ebdf75d1a8bca0122b6dcb34a7efae2a1839919 /fs/proc | |
| parent | 0eb97f38d2bfaea289b44c5140a7b04e7b369bad (diff) | |
sysctl: Comments to make the code clearer.
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>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/proc_sysctl.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 722ec116208..e5601dc2408 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -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); |