1 files changed, 31 insertions, 31 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 4b3b3ffb52f1..c5450183ca78 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -181,14 +181,16 @@ proc_file_read(struct file *file, char __user *buf, size_t nbytes,
 {
 	struct proc_dir_entry *pde = PDE(file_inode(file));
 	ssize_t rv = -EIO;
+	const struct file_operations *fops;
 
-	spin_lock(&pde->pde_unload_lock);
-	if (!pde->proc_fops) {
-		spin_unlock(&pde->pde_unload_lock);
+	rcu_read_lock();
+	fops = rcu_dereference(pde->proc_fops);
+	if (!fops) {
+		rcu_read_unlock();
 		return rv;
 	}
-	pde->pde_users++;
-	spin_unlock(&pde->pde_unload_lock);
+	atomic_inc(&pde->pde_users);
+	rcu_read_unlock();
 
 	rv = __proc_file_read(file, buf, nbytes, ppos);
 
@@ -204,13 +206,16 @@ proc_file_write(struct file *file, const char __user *buffer,
 	ssize_t rv = -EIO;
 
 	if (pde->write_proc) {
-		spin_lock(&pde->pde_unload_lock);
-		if (!pde->proc_fops) {
-			spin_unlock(&pde->pde_unload_lock);
+		const struct file_operations *fops;
+
+		rcu_read_lock();
+		fops = rcu_dereference(pde->proc_fops);
+		if (!fops) {
+			rcu_read_unlock();
 			return rv;
 		}
-		pde->pde_users++;
-		spin_unlock(&pde->pde_unload_lock);
+		atomic_inc(&pde->pde_users);
+		rcu_read_unlock();
 
 		/* FIXME: does this routine need ppos?  probably... */
 		rv = pde->write_proc(file, buffer, count, pde->data);
@@ -542,7 +547,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
 
 	if (S_ISDIR(dp->mode)) {
 		if (dp->proc_iops == NULL) {
-			dp->proc_fops = &proc_dir_operations;
+			RCU_INIT_POINTER(dp->proc_fops, &proc_dir_operations);
 			dp->proc_iops = &proc_dir_inode_operations;
 		}
 		dir->nlink++;
@@ -551,7 +556,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
 			dp->proc_iops = &proc_link_inode_operations;
 	} else if (S_ISREG(dp->mode)) {
 		if (dp->proc_fops == NULL)
-			dp->proc_fops = &proc_file_operations;
+			RCU_INIT_POINTER(dp->proc_fops, &proc_file_operations);
 		if (dp->proc_iops == NULL)
 			dp->proc_iops = &proc_file_inode_operations;
 	}
@@ -604,7 +609,8 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
 	ent->mode = mode;
 	ent->nlink = nlink;
 	atomic_set(&ent->count, 1);
-	spin_lock_init(&ent->pde_unload_lock);
+	atomic_set(&ent->pde_users, 1);
+	spin_lock_init(&ent->pde_openers_lock);
 	INIT_LIST_HEAD(&ent->pde_openers);
 out:
 	return ent;
@@ -728,7 +734,7 @@ struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
 	pde = __proc_create(&parent, name, mode, nlink);
 	if (!pde)
 		goto out;
-	pde->proc_fops = proc_fops;
+	rcu_assign_pointer(pde->proc_fops, proc_fops);
 	pde->data = data;
 	if (proc_register(parent, pde) < 0)
 		goto out_free;
@@ -764,6 +770,7 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
 	struct proc_dir_entry *de = NULL;
 	const char *fn = name;
 	unsigned int len;
+	DECLARE_COMPLETION_ONSTACK(c);
 
 	spin_lock(&proc_subdir_lock);
 	if (__xlate_proc_name(name, &parent, &fn) != 0) {
@@ -786,37 +793,30 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
 		return;
 	}
 
-	spin_lock(&de->pde_unload_lock);
 	/*
 	 * Stop accepting new callers into module. If you're
 	 * dynamically allocating ->proc_fops, save a pointer somewhere.
 	 */
-	de->proc_fops = NULL;
-	/* Wait until all existing callers into module are done. */
-	if (de->pde_users > 0) {
-		DECLARE_COMPLETION_ONSTACK(c);
-
-		if (!de->pde_unload_completion)
-			de->pde_unload_completion = &c;
-
-		spin_unlock(&de->pde_unload_lock);
-
+	rcu_assign_pointer(de->proc_fops, NULL);
+	synchronize_rcu();
+	/*
+	 * Wait until all existing callers into module are done.
+	 * Once pde_users hits zero we are free to clean out pde_openers.
+	 */
+	de->pde_unload_completion = &c;
+	if (!atomic_dec_and_test(&de->pde_users))
 		wait_for_completion(de->pde_unload_completion);
 
-		spin_lock(&de->pde_unload_lock);
-	}
-
+	spin_lock(&de->pde_openers_lock);
 	while (!list_empty(&de->pde_openers)) {
 		struct pde_opener *pdeo;
 
 		pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
 		list_del(&pdeo->lh);
-		spin_unlock(&de->pde_unload_lock);
 		pdeo->release(pdeo->inode, pdeo->file);
 		kfree(pdeo);
-		spin_lock(&de->pde_unload_lock);
 	}
-	spin_unlock(&de->pde_unload_lock);
+	spin_unlock(&de->pde_openers_lock);
 
 	if (S_ISDIR(de->mode))
 		parent->nlink--;