[patch V2 24/29] tracing: Remove the last struct stack_trace usage

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

Simplify the stack retrieval code by using the storage array based
interface.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/trace/trace_stack.c |   42 ++++++++++++++++--------------------------
 1 file changed, 16 insertions(+), 26 deletions(-)

--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -23,16 +23,7 @@
 static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES];
 static unsigned stack_trace_index[STACK_TRACE_ENTRIES];
 
-/*
- * Reserve one entry for the passed in ip. This will allow
- * us to remove most or all of the stack size overhead
- * added by the stack tracer itself.
- */
-struct stack_trace stack_trace_max = {
-	.max_entries		= STACK_TRACE_ENTRIES - 1,
-	.entries		= &stack_dump_trace[0],
-};
-
+static unsigned int stack_trace_entries;
 static unsigned long stack_trace_max_size;
 static arch_spinlock_t stack_trace_max_lock =
 	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
@@ -49,10 +40,10 @@ static void print_max_stack(void)
 
 	pr_emerg("        Depth    Size   Location    (%d entries)\n"
 			   "        -----    ----   --------\n",
-			   stack_trace_max.nr_entries);
+			   stack_trace_entries);
 
-	for (i = 0; i < stack_trace_max.nr_entries; i++) {
-		if (i + 1 == stack_trace_max.nr_entries)
+	for (i = 0; i < stack_trace_entries; i++) {
+		if (i + 1 == stack_trace_entries)
 			size = stack_trace_index[i];
 		else
 			size = stack_trace_index[i] - stack_trace_index[i+1];
@@ -98,13 +89,12 @@ static void check_stack(unsigned long ip
 
 	stack_trace_max_size = this_size;
 
-	stack_trace_max.nr_entries = 0;
-	stack_trace_max.skip = 0;
-
-	save_stack_trace(&stack_trace_max);
+	stack_trace_entries = stack_trace_save(stack_dump_trace,
+					       ARRAY_SIZE(stack_dump_trace) - 1,
+					       0);
 
 	/* Skip over the overhead of the stack tracer itself */
-	for (i = 0; i < stack_trace_max.nr_entries; i++) {
+	for (i = 0; i < stack_trace_entries; i++) {
 		if (stack_dump_trace[i] == ip)
 			break;
 	}
@@ -113,7 +103,7 @@ static void check_stack(unsigned long ip
 	 * Some archs may not have the passed in ip in the dump.
 	 * If that happens, we need to show everything.
 	 */
-	if (i == stack_trace_max.nr_entries)
+	if (i == stack_trace_entries)
 		i = 0;
 
 	/*
@@ -131,13 +121,13 @@ static void check_stack(unsigned long ip
 	 * loop will only happen once. This code only takes place
 	 * on a new max, so it is far from a fast path.
 	 */
-	while (i < stack_trace_max.nr_entries) {
+	while (i < stack_trace_entries) {
 		int found = 0;
 
 		stack_trace_index[x] = this_size;
 		p = start;
 
-		for (; p < top && i < stack_trace_max.nr_entries; p++) {
+		for (; p < top && i < stack_trace_entries; p++) {
 			/*
 			 * The READ_ONCE_NOCHECK is used to let KASAN know that
 			 * this is not a stack-out-of-bounds error.
@@ -168,7 +158,7 @@ static void check_stack(unsigned long ip
 			i++;
 	}
 
-	stack_trace_max.nr_entries = x;
+	stack_trace_entries = x;
 
 	if (task_stack_end_corrupted(current)) {
 		print_max_stack();
@@ -270,7 +260,7 @@ static void *
 {
 	long n = *pos - 1;
 
-	if (n >= stack_trace_max.nr_entries)
+	if (n >= stack_trace_entries)
 		return NULL;
 
 	m->private = (void *)n;
@@ -334,7 +324,7 @@ static int t_show(struct seq_file *m, vo
 		seq_printf(m, "        Depth    Size   Location"
 			   "    (%d entries)\n"
 			   "        -----    ----   --------\n",
-			   stack_trace_max.nr_entries);
+			   stack_trace_entries);
 
 		if (!stack_tracer_enabled && !stack_trace_max_size)
 			print_disabled(m);
@@ -344,10 +334,10 @@ static int t_show(struct seq_file *m, vo
 
 	i = *(long *)v;
 
-	if (i >= stack_trace_max.nr_entries)
+	if (i >= stack_trace_entries)
 		return 0;
 
-	if (i + 1 == stack_trace_max.nr_entries)
+	if (i + 1 == stack_trace_entries)
 		size = stack_trace_index[i];
 	else
 		size = stack_trace_index[i] - stack_trace_index[i+1];