proc: simplify locking in remove_proc_entry()

proc_subdir_lock protects only modifying and walking through PDE lists, so
after we've found PDE to remove and actually removed it from lists, there is
no need to hold proc_subdir_lock for the rest of operation.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/generic.c

@@ -734,21 +734,26 @@ void free_proc_entry(struct proc_dir_entry *de)
 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
 {
 	struct proc_dir_entry **p;
-	struct proc_dir_entry *de;
+	struct proc_dir_entry *de = NULL;
 	const char *fn = name;
 	int len;
 
 	if (!parent && xlate_proc_name(name, &parent, &fn) != 0)
-		goto out;
+		return;
 	len = strlen(fn);
 
 	spin_lock(&proc_subdir_lock);
 	for (p = &parent->subdir; *p; p=&(*p)->next ) {
-		if (!proc_match(len, fn, *p))
-			continue;
+		if (proc_match(len, fn, *p)) {
 			de = *p;
 			*p = de->next;
 			de->next = NULL;
+			break;
+		}
+	}
+	spin_unlock(&proc_subdir_lock);
+	if (!de)
+		return;
 
 	spin_lock(&de->pde_unload_lock);
 	/*
@@ -764,11 +769,9 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
 			de->pde_unload_completion = &c;
 
 		spin_unlock(&de->pde_unload_lock);
-			spin_unlock(&proc_subdir_lock);
 
 		wait_for_completion(de->pde_unload_completion);
 
-			spin_lock(&proc_subdir_lock);
 		goto continue_removing;
 	}
 	spin_unlock(&de->pde_unload_lock);
@@ -785,9 +788,4 @@ continue_removing:
 	}
 	if (atomic_dec_and_test(&de->count))
 		free_proc_entry(de);
-		break;
-	}
-	spin_unlock(&proc_subdir_lock);
-out:
-	return;
 }