linux-kernel - Re: [PATCH] kcov: simplify interrupt check

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Date:   Tue, 21 Mar 2017 17:28:19 +0800
From:   "Hillf Danton" <hillf.zj@...baba-inc.com>
To:     "'Dmitry Vyukov'" <dvyukov@...gle.com>,
        <akpm@...ux-foundation.org>, <linux-mm@...ck.org>
Cc:     "'Kefeng Wang'" <wangkefeng.wang@...wei.com>,
        "'James Morse'" <james.morse@....com>,
        "'Alexander Popov'" <alex.popov@...ux.com>,
        "'Andrey Konovalov'" <andreyknvl@...gle.com>,
        <linux-kernel@...r.kernel.org>, <syzkaller@...glegroups.com>
Subject: Re: [PATCH] kcov: simplify interrupt check


On March 21, 2017 5:10 PM Dmitry Vyukov wrote: 
> 
> @@ -60,15 +60,8 @@ void notrace __sanitizer_cov_trace_pc(void)
>  	/*
>  	 * We are interested in code coverage as a function of a syscall inputs,
>  	 * so we ignore code executed in interrupts.
> -	 * The checks for whether we are in an interrupt are open-coded, because
> -	 * 1. We can't use in_interrupt() here, since it also returns true
> -	 *    when we are inside local_bh_disable() section.
> -	 * 2. We don't want to use (in_irq() | in_serving_softirq() | in_nmi()),
> -	 *    since that leads to slower generated code (three separate tests,
> -	 *    one for each of the flags).
>  	 */
> -	if (!t || (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_OFFSET
> -							| NMI_MASK)))
> +	if (!t || !in_task())
>  		return;

Nit: can we get the current task check cut off?