tracing: Remove the last struct stack_trace usage

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094803.340000461@linutronix.de

kernel/trace/trace_stack.c

@@ -23,11 +23,7 @@
 static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES];
 static unsigned stack_trace_index[STACK_TRACE_ENTRIES];
 
-struct stack_trace stack_trace_max = {
-	.max_entries		= STACK_TRACE_ENTRIES,
-	.entries		= &stack_dump_trace[0],
-};
-
+static unsigned int stack_trace_nr_entries;
 static unsigned long stack_trace_max_size;
 static arch_spinlock_t stack_trace_max_lock =
 	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
@@ -44,10 +40,10 @@ static void print_max_stack(void)
 
 	pr_emerg("        Depth    Size   Location    (%d entries)\n"
 			   "        -----    ----   --------\n",
-			   stack_trace_max.nr_entries);
+			   stack_trace_nr_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_nr_entries; i++) {
+		if (i + 1 == stack_trace_nr_entries)
 			size = stack_trace_index[i];
 		else
 			size = stack_trace_index[i] - stack_trace_index[i+1];
@@ -93,13 +89,12 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 
 	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_nr_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_nr_entries; i++) {
 		if (stack_dump_trace[i] == ip)
 			break;
 	}
@@ -108,7 +103,7 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 	 * 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_nr_entries)
 		i = 0;
 
 	/*
@@ -126,13 +121,13 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 	 * 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_nr_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_nr_entries; p++) {
 			/*
 			 * The READ_ONCE_NOCHECK is used to let KASAN know that
 			 * this is not a stack-out-of-bounds error.
@@ -163,7 +158,7 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 			i++;
 	}
 
-	stack_trace_max.nr_entries = x;
+	stack_trace_nr_entries = x;
 
 	if (task_stack_end_corrupted(current)) {
 		print_max_stack();
@@ -265,7 +260,7 @@ __next(struct seq_file *m, loff_t *pos)
 {
 	long n = *pos - 1;
 
-	if (n >= stack_trace_max.nr_entries)
+	if (n >= stack_trace_nr_entries)
 		return NULL;
 
 	m->private = (void *)n;
@@ -329,7 +324,7 @@ static int t_show(struct seq_file *m, void *v)
 		seq_printf(m, "        Depth    Size   Location"
 			   "    (%d entries)\n"
 			   "        -----    ----   --------\n",
-			   stack_trace_max.nr_entries);
+			   stack_trace_nr_entries);
 
 		if (!stack_tracer_enabled && !stack_trace_max_size)
 			print_disabled(m);
@@ -339,10 +334,10 @@ static int t_show(struct seq_file *m, void *v)
 
 	i = *(long *)v;
 
-	if (i >= stack_trace_max.nr_entries)
+	if (i >= stack_trace_nr_entries)
 		return 0;
 
-	if (i + 1 == stack_trace_max.nr_entries)
+	if (i + 1 == stack_trace_nr_entries)
 		size = stack_trace_index[i];
 	else
 		size = stack_trace_index[i] - stack_trace_index[i+1];