From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-block@vger.kernel.org
Subject: Re: [PATCH 3/3] block: only allocate poll_stats if there's a user of them
Date: Tue, 23 Nov 2021 12:03:26 -0700 [thread overview]
Message-ID: <effc7077-4b49-5508-fb35-19db49c82488@kernel.dk> (raw)
In-Reply-To: <YZ06Kd6qpRPt3KG4@infradead.org>
On 11/23/21 11:59 AM, Christoph Hellwig wrote:
> On Tue, Nov 23, 2021 at 11:58:42AM -0700, Jens Axboe wrote:
>> On 11/23/21 11:50 AM, Christoph Hellwig wrote:
>>>> + spin_lock_irq(&q->stats->lock);
>>>> + if (q->poll_stat) {
>>>> + spin_unlock_irq(&q->stats->lock);
>>>> + kfree(poll_stat);
>>>> + return true;
>>>> + }
>>>> + q->poll_stat = poll_stat;
>>>> + spin_unlock_irq(&q->stats->lock);
>>>
>>> If we'd use a cmpxchg to install the pointer we could keep the
>>> blk_queue_stats definition private.
>>
>> How about we just move this alloc+enable logic into blk-stat.c instead?
>
> That's a good idea either way. But I think cmpxchg is much better
> for installing a pointer than an unrelated lock.
True, I'll do that while moving it.
--
Jens Axboe
next prev parent reply other threads:[~2021-11-23 19:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 17:10 [PATCHSET 0/3 v2] Misc block cleanups Jens Axboe
2021-11-23 17:10 ` [PATCH 1/3] block: move io_context creation into where it's needed Jens Axboe
2021-11-23 18:46 ` Christoph Hellwig
2021-11-23 18:58 ` Jens Axboe
2021-11-23 17:10 ` [PATCH 2/3] blk-ioprio: don't set bio priority if not needed Jens Axboe
2021-11-23 18:51 ` Christoph Hellwig
2021-11-23 17:10 ` [PATCH 3/3] block: only allocate poll_stats if there's a user of them Jens Axboe
2021-11-23 18:50 ` Christoph Hellwig
2021-11-23 18:58 ` Jens Axboe
2021-11-23 18:59 ` Christoph Hellwig
2021-11-23 19:03 ` Jens Axboe [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-11-23 16:18 [PATCHSET 0/3] Misc block cleanups Jens Axboe
2021-11-23 16:18 ` [PATCH 3/3] block: only allocate poll_stats if there's a user of them Jens Axboe
2021-11-23 16:21 ` Johannes Thumshirn
2021-11-23 16:27 ` Jens Axboe
2021-11-23 16:41 ` Christoph Hellwig
2021-11-23 16:44 ` Jens Axboe
2021-11-23 17:05 ` Christoph Hellwig
2021-11-23 17:06 ` Jens Axboe
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