From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Paolo Valente <paolo.valente@linaro.org>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 6/7] block: cleanup ioc_clear_queue
Date: Wed, 1 Dec 2021 08:27:02 +0100 [thread overview]
Message-ID: <20211201072702.GB31765@lst.de> (raw)
In-Reply-To: <20211130172613.GL7174@quack2.suse.cz>
On Tue, Nov 30, 2021 at 06:26:13PM +0100, Jan Kara wrote:
> I'm not quite sure about dropping the rcu protection here. This function
> generally runs without any protection so what guards us against icq being
> freed just after we've got its pointer from the list?
How does the RCU protection scheme work for the icq lookups?
ioc_lookup_icq takes it and then drops it before getting any kind
of refcount, so this all looks weird. But I guess you are right that
I should probably keep this cargo culted scheme unless I have an
actual plan on how this could work.
While we're at it: I don't see how put put_io_context could
be called under q->queue_lock and thus actually need the whole
workqueue scheme. Then again we really need to do an audit on
queue_lock and split it into actually documented locks now that the
old request code is gone.
next prev parent reply other threads:[~2021-12-01 7:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 12:46 more I/O context cleanup Christoph Hellwig
2021-11-30 12:46 ` [PATCH 1/7] block: remove the nr_task field from struct io_context Christoph Hellwig
2021-11-30 15:43 ` Jan Kara
2021-11-30 12:46 ` [PATCH 2/7] block: simplify struct io_context refcounting Christoph Hellwig
2021-11-30 15:02 ` Jan Kara
2021-11-30 12:46 ` [PATCH 3/7] block: refactor put_iocontext_active Christoph Hellwig
2021-11-30 15:01 ` Jan Kara
2021-11-30 12:46 ` [PATCH 4/7] block: remove the NULL ioc check in put_io_context Christoph Hellwig
2021-11-30 14:59 ` Jan Kara
2021-11-30 12:46 ` [PATCH 5/7] block: refactor put_io_context Christoph Hellwig
2021-11-30 14:58 ` Jan Kara
2021-11-30 12:46 ` [PATCH 6/7] block: cleanup ioc_clear_queue Christoph Hellwig
2021-11-30 17:26 ` Jan Kara
2021-12-01 7:27 ` Christoph Hellwig [this message]
2021-12-01 14:33 ` Jan Kara
2021-11-30 12:46 ` [PATCH 7/7] block: only build the icq tracking code when needed Christoph Hellwig
2021-11-30 17:27 ` Jan Kara
2021-12-05 13:04 ` [block] 8216260d3a: BUG:sleeping_function_called_from_invalid_context_at_arch/x86/mm/fault.c kernel test robot
2021-12-05 13:04 ` kernel test robot
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