try a saner locking for pde_opener...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index b5b204d..3b14a45 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -133,67 +133,48 @@
static inline int use_pde(struct proc_dir_entry *pde)
{
- int res = 1;
- spin_lock(&pde->pde_unload_lock);
- if (unlikely(pde->pde_users < 0))
- res = 0;
- else
- pde->pde_users++;
- spin_unlock(&pde->pde_unload_lock);
- return res;
-}
-
-static void __pde_users_dec(struct proc_dir_entry *pde)
-{
- if (--pde->pde_users == BIAS)
- complete(pde->pde_unload_completion);
+ return atomic_inc_unless_negative(&pde->in_use);
}
static void unuse_pde(struct proc_dir_entry *pde)
{
- spin_lock(&pde->pde_unload_lock);
- __pde_users_dec(pde);
- spin_unlock(&pde->pde_unload_lock);
+ if (atomic_dec_return(&pde->in_use) == BIAS)
+ complete(pde->pde_unload_completion);
}
/* pde is locked */
static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
{
- pdeo->count++;
- if (!mutex_trylock(&pdeo->mutex)) {
+ if (pdeo->closing) {
/* somebody else is doing that, just wait */
+ DECLARE_COMPLETION_ONSTACK(c);
+ pdeo->c = &c;
spin_unlock(&pde->pde_unload_lock);
- mutex_lock(&pdeo->mutex);
+ wait_for_completion(&c);
spin_lock(&pde->pde_unload_lock);
- WARN_ON(!list_empty(&pdeo->lh));
} else {
struct file *file;
+ pdeo->closing = 1;
spin_unlock(&pde->pde_unload_lock);
file = pdeo->file;
pde->proc_fops->release(file_inode(file), file);
spin_lock(&pde->pde_unload_lock);
list_del_init(&pdeo->lh);
- }
- mutex_unlock(&pdeo->mutex);
- if (!--pdeo->count)
+ if (pdeo->c)
+ complete(pdeo->c);
kfree(pdeo);
+ }
}
void proc_entry_rundown(struct proc_dir_entry *de)
{
- spin_lock(&de->pde_unload_lock);
- de->pde_users += BIAS;
+ DECLARE_COMPLETION_ONSTACK(c);
/* Wait until all existing callers into module are done. */
- if (de->pde_users != BIAS) {
- DECLARE_COMPLETION_ONSTACK(c);
- de->pde_unload_completion = &c;
- spin_unlock(&de->pde_unload_lock);
+ de->pde_unload_completion = &c;
+ if (atomic_add_return(BIAS, &de->in_use) != BIAS)
+ wait_for_completion(&c);
- wait_for_completion(de->pde_unload_completion);
-
- spin_lock(&de->pde_unload_lock);
- }
-
+ spin_lock(&de->pde_unload_lock);
while (!list_empty(&de->pde_openers)) {
struct pde_opener *pdeo;
pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
@@ -356,7 +337,7 @@
* by hand in remove_proc_entry(). For this, save opener's credentials
* for later.
*/
- pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL);
+ pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
if (!pdeo)
return -ENOMEM;
@@ -370,18 +351,17 @@
if (open)
rv = open(inode, file);
- spin_lock(&pde->pde_unload_lock);
if (rv == 0 && release) {
/* To know what to release. */
- mutex_init(&pdeo->mutex);
- pdeo->count = 0;
pdeo->file = file;
/* Strictly for "too late" ->release in proc_reg_release(). */
+ spin_lock(&pde->pde_unload_lock);
list_add(&pdeo->lh, &pde->pde_openers);
+ spin_unlock(&pde->pde_unload_lock);
} else
kfree(pdeo);
- __pde_users_dec(pde);
- spin_unlock(&pde->pde_unload_lock);
+
+ unuse_pde(pde);
return rv;
}