[tip:core/stacktrace] latency_top: Simplify stack trace handling

[tip-bot for Thomas Gleixner]

Commit-ID:  f93877214a83e88373b20801c2d671923d03d07d
Gitweb:     https://git.kernel.org/tip/f93877214a83e88373b20801c2d671923d03d07d
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 25 Apr 2019 11:44:59 +0200
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 29 Apr 2019 12:37:48 +0200

latency_top: Simplify stack trace handling

Replace the indirection through struct stack_trace with an invocation of
the storage array based interface.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Cc: linux-btrfs@xxxxxxxxxxxxxxx
Cc: dm-devel@xxxxxxxxxx
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Cc: Miroslav Benes <mbenes@xxxxxxx>
Cc: linux-arch@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20190425094801.683039030@xxxxxxxxxxxxx

---
 kernel/latencytop.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/kernel/latencytop.c b/kernel/latencytop.c
index f5a90ab3c6b9..99a5b5f46dc5 100644
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -141,20 +141,6 @@ account_global_scheduler_latency(struct task_struct *tsk,
 	memcpy(&latency_record[i], lat, sizeof(struct latency_record));
 }
 
-/*
- * Iterator to store a backtrace into a latency record entry
- */
-static inline void store_stacktrace(struct task_struct *tsk,
-					struct latency_record *lat)
-{
-	struct stack_trace trace;
-
-	memset(&trace, 0, sizeof(trace));
-	trace.max_entries = LT_BACKTRACEDEPTH;
-	trace.entries = &lat->backtrace[0];
-	save_stack_trace_tsk(tsk, &trace);
-}
-
 /**
  * __account_scheduler_latency - record an occurred latency
  * @tsk - the task struct of the task hitting the latency
@@ -191,7 +177,8 @@ __account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
 	lat.count = 1;
 	lat.time = usecs;
 	lat.max = usecs;
-	store_stacktrace(tsk, &lat);
+
+	stack_trace_save_tsk(tsk, lat.backtrace, LT_BACKTRACEDEPTH, 0);
 
 	raw_spin_lock_irqsave(&latency_lock, flags);