linux-kernel - Re: [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

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Date:   Wed, 10 Apr 2019 21:55:09 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org
Subject: Re: [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

On Wed, Apr 10, 2019 at 12:28:19PM +0200, Thomas Gleixner wrote:
> Replace the indirection through struct stack_trace by using the storage
> array based interfaces.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Cc: Alexander Potapenko <glider@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: kasan-dev@...glegroups.com
> Cc: linux-mm@...ck.org
> ---
>  mm/kasan/common.c |   30 ++++++++++++------------------
>  mm/kasan/report.c |    7 ++++---
>  2 files changed, 16 insertions(+), 21 deletions(-)
> 
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -48,34 +48,28 @@ static inline int in_irqentry_text(unsig
>  		 ptr < (unsigned long)&__softirqentry_text_end);
>  }
>  
> -static inline void filter_irq_stacks(struct stack_trace *trace)
> +static inline unsigned int filter_irq_stacks(unsigned long *entries,
> +					     unsigned int nr_entries)
>  {
> -	int i;
> +	unsigned int i;
>  
> -	if (!trace->nr_entries)
> -		return;
> -	for (i = 0; i < trace->nr_entries; i++)
> -		if (in_irqentry_text(trace->entries[i])) {
> +	for (i = 0; i < nr_entries; i++) {
> +		if (in_irqentry_text(entries[i])) {
>  			/* Include the irqentry function into the stack. */
> -			trace->nr_entries = i + 1;
> -			break;
> +			return i + 1;

Isn't this an off-by-one error if "i" points to the last entry of the
array?

-- 
Josh