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Date: Mon, 14 Jan 2019 11:09:32 -0600
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Joe Lawrence <joe.lawrence@redhat.com>
Subject: Re: ppc64le reliable stack unwinder and scheduled tasks
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Cc: Nicolai Stange <nstange@suse.de>, linux-kernel@vger.kernel.org,
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On Mon, Jan 14, 2019 at 11:46:59AM -0500, Joe Lawrence wrote:
> @@ -158,11 +158,21 @@ save_stack_trace_tsk_reliable(struct task_struct *tsk,
>  			return 1; /* invalid backlink, too far up. */
>  		}
>  
> +		/* We can only trust the bottom frame's backlink, the rest
> +		 * of the frame may be uninitialized, continue to the next. */
> +		if (firstframe--)
> +			goto next;

Won't this decrement firstframe on every iteration, so when firstframe
is 0, it will decrement it to -1, causing it to 'goto next' on all
future iterations?

-- 
Josh