From 5ef19e65e27653ec0ae672398561a6d2b8b58d15 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Thu, 28 Apr 2016 16:19:09 -0700
Subject: [PATCH] UPSTREAM: lib/stackdepot.c: allow the stack trace hash to be
 zero

Do not bail out from depot_save_stack() if the stack trace has zero hash.
Initially depot_save_stack() silently dropped stack traces with zero
hashes, however there's actually no point in reserving this zero value.

Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Bug: 64145065
(cherry-picked from 33334e25769c6ad69b983379578f42581d99a2f9)
Change-Id: I44c9c5a881e2f4176c3946905b8f11b26f45bc00
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 lib/stackdepot.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 654c9d87e83a..9e0b0315a724 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -210,10 +210,6 @@ depot_stack_handle_t depot_save_stack(struct stack_trace *trace,
 		goto fast_exit;
 
 	hash = hash_stack(trace->entries, trace->nr_entries);
-	/* Bad luck, we won't store this stack. */
-	if (hash == 0)
-		goto exit;
-
 	bucket = &stack_table[hash & STACK_HASH_MASK];
 
 	/*