[Devel] [PATCH RHEL7 COMMIT] lib/stackdepot.c: allow the stack trace hash to be zero

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.vz7.37.4
------>
commit d44320c014859863317b1e1885a2d274fba8cea9
Author: Alexander Potapenko <glider at google.com>
Date:   Fri Sep 15 17:17:49 2017 +0300

    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 at lge.com>
    Signed-off-by: Alexander Potapenko <glider at google.com>
    Acked-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-69081
    (cherry picked from commit 33334e25769c6ad69b983379578f42581d99a2f9)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 lib/stackdepot.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 654c9d8..9e0b031 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];
 
 	/*