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Message-ID: <20200504140044.GA29020@infradead.org>
Date: Mon, 4 May 2020 07:00:44 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH 1/4] block/part_stat: remove rcu_read_lock() from
part_stat_lock()
On Mon, May 04, 2020 at 04:29:29PM +0300, Konstantin Khlebnikov wrote:
> RCU lock is required only in blk_account_io_start() to lookup partition.
> After that request holds reference to related hd_struct.
>
> Replace get_cpu() with preempt_disable() - returned cpu index is unused.
>
> Non-SMP case also needs preempt_disable, otherwise statistics update could
> be non-atomic. Previously that was provided by rcu_read_lock().
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Looks good,
Signed-off-by: Christoph Hellwig <hch@....de>
although I wonder if we should just kill off part_stat_lock and
part_stat_unlock.
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