[RFC 03/14] fork: Clean-up naming of vm_strack/vm_struct variables in vmap stacks code

[Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>]

There are two data types: "struct vm_struct" and "struct vm_stack" that
have the same local variable names: vm_stack, or vm, or s, which makes
code confusing to read.

Change the code so the naming is consisent:

struct vm_struct is always called vm_area
struct vm_stack is always called vm_stack

Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
---
 kernel/fork.c | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 32600bf2422a..60e812825a7a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -192,12 +192,12 @@ struct vm_stack {
 	struct vm_struct *stack_vm_area;
 };
 
-static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
+static bool try_release_thread_stack_to_cache(struct vm_struct *vm_area)
 {
 	unsigned int i;
 
 	for (i = 0; i < NR_CACHED_STACKS; i++) {
-		if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
+		if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm_area) != NULL)
 			continue;
 		return true;
 	}
@@ -207,11 +207,12 @@ static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
 static void thread_stack_free_rcu(struct rcu_head *rh)
 {
 	struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
+	struct vm_struct *vm_area = vm_stack->stack_vm_area;
 
 	if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
 		return;
 
-	vfree(vm_stack);
+	vfree(vm_area->addr);
 }
 
 static void thread_stack_delayed_free(struct task_struct *tsk)
@@ -228,12 +229,12 @@ static int free_vm_stack_cache(unsigned int cpu)
 	int i;
 
 	for (i = 0; i < NR_CACHED_STACKS; i++) {
-		struct vm_struct *vm_stack = cached_vm_stacks[i];
+		struct vm_struct *vm_area = cached_vm_stacks[i];
 
-		if (!vm_stack)
+		if (!vm_area)
 			continue;
 
-		vfree(vm_stack->addr);
+		vfree(vm_area->addr);
 		cached_vm_stacks[i] = NULL;
 	}
 
@@ -263,32 +264,29 @@ static int memcg_charge_kernel_stack(struct vm_struct *vm)
 
 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
 {
-	struct vm_struct *vm;
+	struct vm_struct *vm_area;
 	void *stack;
 	int i;
 
 	for (i = 0; i < NR_CACHED_STACKS; i++) {
-		struct vm_struct *s;
-
-		s = this_cpu_xchg(cached_stacks[i], NULL);
-
-		if (!s)
+		vm_area = this_cpu_xchg(cached_stacks[i], NULL);
+		if (!vm_area)
 			continue;
 
 		/* Reset stack metadata. */
-		kasan_unpoison_range(s->addr, THREAD_SIZE);
+		kasan_unpoison_range(vm_area->addr, THREAD_SIZE);
 
-		stack = kasan_reset_tag(s->addr);
+		stack = kasan_reset_tag(vm_area->addr);
 
 		/* Clear stale pointers from reused stack. */
 		memset(stack, 0, THREAD_SIZE);
 
-		if (memcg_charge_kernel_stack(s)) {
-			vfree(s->addr);
+		if (memcg_charge_kernel_stack(vm_area)) {
+			vfree(vm_area->addr);
 			return -ENOMEM;
 		}
 
-		tsk->stack_vm_area = s;
+		tsk->stack_vm_area = vm_area;
 		tsk->stack = stack;
 		return 0;
 	}
@@ -306,8 +304,8 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
 	if (!stack)
 		return -ENOMEM;
 
-	vm = find_vm_area(stack);
-	if (memcg_charge_kernel_stack(vm)) {
+	vm_area = find_vm_area(stack);
+	if (memcg_charge_kernel_stack(vm_area)) {
 		vfree(stack);
 		return -ENOMEM;
 	}
@@ -316,7 +314,7 @@ static int alloc_thread_stack_node(struct task_struct *tsk, int node)
 	 * free_thread_stack() can be called in interrupt context,
 	 * so cache the vm_struct.
 	 */
-	tsk->stack_vm_area = vm;
+	tsk->stack_vm_area = vm_area;
 	stack = kasan_reset_tag(stack);
 	tsk->stack = stack;
 	return 0;
-- 
2.44.0.278.ge034bb2e1d-goog