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Subject: Re: [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Sagi Grimberg <sagi@grimberg.me>
Cc:     Christoph Hellwig <hch@infradead.org>, linux-block@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        David Runge <dave@sleepmap.de>, linux-rt-users@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Daniel Wagner <dwagner@suse.de>, Mike Galbraith <efault@gmx.de>
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 <20201029140536.GA6376@infradead.org>
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 <20201031104108.wjjdiklqrgyqmj54@linutronix.de>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <3bbfb5e1-c5d7-8f3b-4b96-6dc02be0550d@kernel.dk>
Date:   Sat, 31 Oct 2020 09:00:49 -0600
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On 10/31/20 4:41 AM, Sebastian Andrzej Siewior wrote:
> On 2020-10-29 14:07:59 [-0700], Sagi Grimberg wrote:
>>> in which context?
>>
>> Not sure what is the question.
> 
> The question is in which context do you complete your requests. My guess
> by now is "usually softirq/NAPI and context in rare error case".

There really aren't any rules for this, and it's perfectly legit to
complete from process context. Maybe you're a kthread driven driver and
that's how you handle completions. The block completion path has always
been hard IRQ safe, but possible to call from anywhere.

-- 
Jens Axboe