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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "'Dmitry Vyukov'" <dvyukov@google.com>, <akpm@linux-foundation.org>,
        <linux-mm@kvack.org>
Cc: "'Kefeng Wang'" <wangkefeng.wang@huawei.com>,
        "'James Morse'" <james.morse@arm.com>,
        "'Alexander Popov'" <alex.popov@linux.com>,
        "'Andrey Konovalov'" <andreyknvl@google.com>,
        <linux-kernel@vger.kernel.org>, <syzkaller@googlegroups.com>
References: <20170321091026.139655-1-dvyukov@google.com>
In-Reply-To: <20170321091026.139655-1-dvyukov@google.com>
Subject: Re: [PATCH] kcov: simplify interrupt check
Date: Tue, 21 Mar 2017 17:28:19 +0800
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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?