From: Christoph Hellwig <hch@infradead.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
Song Liu <song@kernel.org>, Christoph Hellwig <hch@infradead.org>,
Donald Buczek <buczek@molgen.mpg.de>,
Guoqing Jiang <guoqing.jiang@linux.dev>, Xiao Ni <xni@redhat.com>,
Stephen Bates <sbates@raithlin.com>,
Martin Oliveira <Martin.Oliveira@eideticom.com>,
David Sloan <David.Sloan@eideticom.com>
Subject: Re: [PATCH v3 05/11] md/raid5-cache: Drop RCU usage of conf->log
Date: Thu, 2 Jun 2022 23:43:05 -0700 [thread overview]
Message-ID: <YpmteYBT71dYY7t0@infradead.org> (raw)
In-Reply-To: <20220602181818.50729-6-logang@deltatee.com>
On Thu, Jun 02, 2022 at 12:18:11PM -0600, Logan Gunthorpe wrote:
> The only place that uses RCU to access conf->log is in
> r5l_log_disk_error(). This function is mostly used in the IO path
> and once with mddev_lock() held in raid5_change_consistency_policy().
>
> It is known that the IO will be suspended before the log is freed and
> r5l_log_exit() is called with the mddev_lock() held.
>
> This should mean that conf->log can not be freed while the function is
> being called, so the RCU protection is not necessary. Drop the
> rcu_read_lock() as well as the synchronize_rcu() and
> rcu_assign_pointer() usage.
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2022-06-03 6:43 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-02 18:18 [PATCH v3 00/11] Bug fixes for mdadm tests Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 01/11] md/raid5-log: Drop extern decorators for function prototypes Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 02/11] md/raid5-ppl: Drop unused argument from ppl_handle_flush_request() Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 03/11] md/raid5: Ensure array is suspended for calls to log_exit() Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 04/11] md/raid5-cache: Take mddev_lock in r5c_journal_mode_show() Logan Gunthorpe
2022-06-03 6:39 ` Christoph Hellwig
2022-06-03 21:47 ` Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 05/11] md/raid5-cache: Drop RCU usage of conf->log Logan Gunthorpe
2022-06-03 6:43 ` Christoph Hellwig [this message]
2022-06-02 18:18 ` [PATCH v3 06/11] md/raid5-cache: Clear conf->log after finishing work Logan Gunthorpe
2022-06-03 6:43 ` Christoph Hellwig
2022-06-02 18:18 ` [PATCH v3 07/11] md/raid5-cache: Annotate pslot with __rcu notation Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 08/11] md: Use enum for overloaded magic numbers used by mddev->curr_resync Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 09/11] md: Ensure resync is reported after it starts Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 10/11] md: Notify sysfs sync_completed in md_reap_sync_thread() Logan Gunthorpe
2022-06-02 18:18 ` [PATCH v3 11/11] md/raid5-ppl: Fix argument order in bio_alloc_bioset() Logan Gunthorpe
2022-06-03 6:45 ` Christoph Hellwig
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