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procfs: add proc_remove_subtree()

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just what it sounds like; do that only to procfs subtrees you've
created - doing that to something shared with another driver is
not only antisocial, but might cause interesting races with
proc_create() and its ilk.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-03-30 20:13:46 -04:00
parent 52f21999c7
commit 8ce584c741
2 changed files with 91 additions and 30 deletions
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119
fs/proc/generic.c
View File

@ -755,37 +755,8 @@ void pde_put(struct proc_dir_entry *pde)
free_proc_entry(pde);
}
/*
* Remove a /proc entry and free it if it's not currently in use.
*/
void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
static void entry_rundown(struct proc_dir_entry *de)
{
struct proc_dir_entry **p;
struct proc_dir_entry *de = NULL;
const char *fn = name;
unsigned int len;
spin_lock(&proc_subdir_lock);
if (__xlate_proc_name(name, &parent, &fn) != 0) {
spin_unlock(&proc_subdir_lock);
return;
}
len = strlen(fn);
for (p = &parent->subdir; *p; p=&(*p)->next ) {
if (proc_match(len, fn, *p)) {
de = *p;
*p = de->next;
de->next = NULL;
break;
}
}
spin_unlock(&proc_subdir_lock);
if (!de) {
WARN(1, "name '%s'\n", name);
return;
}
spin_lock(&de->pde_unload_lock);
/*
* Stop accepting new callers into module. If you're
@ -817,6 +788,40 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
spin_lock(&de->pde_unload_lock);
}
spin_unlock(&de->pde_unload_lock);
}
/*
* Remove a /proc entry and free it if it's not currently in use.
*/
void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
{
struct proc_dir_entry **p;
struct proc_dir_entry *de = NULL;
const char *fn = name;
unsigned int len;
spin_lock(&proc_subdir_lock);
if (__xlate_proc_name(name, &parent, &fn) != 0) {
spin_unlock(&proc_subdir_lock);
return;
}
len = strlen(fn);
for (p = &parent->subdir; *p; p=&(*p)->next ) {
if (proc_match(len, fn, *p)) {
de = *p;
*p = de->next;
de->next = NULL;
break;
}
}
spin_unlock(&proc_subdir_lock);
if (!de) {
WARN(1, "name '%s'\n", name);
return;
}
entry_rundown(de);
if (S_ISDIR(de->mode))
parent->nlink--;
@ -827,3 +832,57 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
pde_put(de);
}
EXPORT_SYMBOL(remove_proc_entry);
int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
{
struct proc_dir_entry **p;
struct proc_dir_entry *root = NULL, *de, *next;
const char *fn = name;
unsigned int len;
spin_lock(&proc_subdir_lock);
if (__xlate_proc_name(name, &parent, &fn) != 0) {
spin_unlock(&proc_subdir_lock);
return -ENOENT;
}
len = strlen(fn);
for (p = &parent->subdir; *p; p=&(*p)->next ) {
if (proc_match(len, fn, *p)) {
root = *p;
*p = root->next;
root->next = NULL;
break;
}
}
if (!root) {
spin_unlock(&proc_subdir_lock);
return -ENOENT;
}
de = root;
while (1) {
next = de->subdir;
if (next) {
de->subdir = next->next;
next->next = NULL;
de = next;
continue;
}
spin_unlock(&proc_subdir_lock);
entry_rundown(de);
next = de->parent;
if (S_ISDIR(de->mode))
next->nlink--;
de->nlink = 0;
if (de == root)
break;
pde_put(de);
spin_lock(&proc_subdir_lock);
de = next;
}
pde_put(root);
return 0;
}
EXPORT_SYMBOL(remove_proc_subtree);

2
include/linux/proc_fs.h
View File

@ -117,6 +117,7 @@ struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
const struct file_operations *proc_fops,
void *data);
extern void remove_proc_entry(const char *name, struct proc_dir_entry *parent);
extern int remove_proc_subtree(const char *name, struct proc_dir_entry *parent);
struct pid_namespace;
@ -202,6 +203,7 @@ static inline struct proc_dir_entry *proc_create_data(const char *name,
return NULL;
}
#define remove_proc_entry(name, parent) do {} while (0)
#define remove_proc_subtree(name, parent) do {} while (0)
static inline struct proc_dir_entry *proc_symlink(const char *name,
struct proc_dir_entry *parent,const char *dest) {return NULL;}