From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
Song Liu <song@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Veronika Kabatova <vkabatov@redhat.com>,
linux-raid@vger.kernel.org, Sagi Grimberg <sagi@grimberg.me>,
Tejun Heo <tj@kernel.org>, Christoph Hellwig <hch@lst.de>,
Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH V5 1/3] percpu_ref: add percpu_ref_is_initialized for MD
Date: Mon, 28 Sep 2020 09:30:28 +0200 [thread overview]
Message-ID: <20200928073028.GA16536@lst.de> (raw)
In-Reply-To: <20200927062654.2750277-2-ming.lei@redhat.com>
On Sun, Sep 27, 2020 at 02:26:52PM +0800, Ming Lei wrote:
> MD code uses perpcu-refcount internal to check if this percpu-refcount
> variable is initialized, this way is a hack.
>
> Add percpu_ref_is_initialized for MD so that the hack can be avoided.
>
> Acked-by: Song Liu <song@kernel.org>
> Suggested-by: Jens Axboe <axboe@kernel.dk>
> Tested-by: Veronika Kabatova <vkabatov@redhat.com>
> Cc: Song Liu <song@kernel.org>
> Cc: linux-raid@vger.kernel.org
> Cc: Sagi Grimberg <sagi@grimberg.me>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> drivers/md/md.c | 2 +-
> include/linux/percpu-refcount.h | 1 +
> lib/percpu-refcount.c | 6 ++++++
> 3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index de8419b7ae98..241ff618d84e 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5631,7 +5631,7 @@ static void no_op(struct percpu_ref *r) {}
>
> int mddev_init_writes_pending(struct mddev *mddev)
> {
> - if (mddev->writes_pending.percpu_count_ptr)
> + if (percpu_ref_is_initialized(&mddev->writes_pending))
> return 0;
I'd much rather use a flag in the containing mddev structure then
exposing this new "API". That mddev code is pretty gross to be honest,
we should just initialize the percpu_ref once instea of such a hack.
next prev parent reply other threads:[~2020-09-28 7:30 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-27 6:26 [PATCH V5 0/3] percpu_ref & block: reduce memory footprint of percpu_ref in fast path Ming Lei
2020-09-27 6:26 ` [PATCH V5 1/3] percpu_ref: add percpu_ref_is_initialized for MD Ming Lei
2020-09-28 7:30 ` Christoph Hellwig [this message]
2020-09-27 6:26 ` [PATCH V5 2/3] percpu_ref: reduce memory footprint of percpu_ref in fast path Ming Lei
2020-09-27 6:26 ` [PATCH V5 3/3] block: move 'q_usage_counter' into front of 'request_queue' Ming Lei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200928073028.GA16536@lst.de \
--to=hch@lst.de \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=sagi@grimberg.me \
--cc=song@kernel.org \
--cc=tj@kernel.org \
--cc=vkabatov@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.