linux-kernel - Re: [PATCH v2] lib/stackdepot.c: allow the stack trace hash to be zero

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Date:	Fri, 15 Apr 2016 19:27:11 +0300
From:	Andrey Ryabinin <ryabinin.a.a@...il.com>
To:	Alexander Potapenko <glider@...gle.com>, adech.fo@...il.com,
	dvyukov@...gle.com, cl@...ux.com, akpm@...ux-foundation.org,
	kcc@...gle.com, iamjoonsoo.kim@....com
Cc:	kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH v2] lib/stackdepot.c: allow the stack trace hash to be
 zero



On 04/13/2016 03:07 PM, Alexander Potapenko wrote:
> 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@....com>
> Signed-off-by: Alexander Potapenko <glider@...gle.com>

Acked-by: Andrey Ryabinin <aryabinin@...tuozzo.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];
>  
>  	/*
>