From: Oleg Nesterov <oleg@redhat.com>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, akpm@linux-foundation.org,
Zach Brown <zab@redhat.com>, Felipe Balbi <balbi@ti.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mark Fasheh <mfasheh@suse.com>, Joel Becker <jlbec@evilplan.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Jens Axboe <axboe@kernel.dk>,
Asai Thambi S P <asamymuthupa@micron.com>,
Selvan Mani <smani@micron.com>,
Sam Bradshaw <sbradshaw@micron.com>,
Jeff Moyer <jmoyer@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
Benjamin LaHaise <bcrl@kvack.org>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 04/21] Generic percpu refcounting
Date: Tue, 14 May 2013 15:51:01 +0200 [thread overview]
Message-ID: <20130514135101.GB17587@redhat.com> (raw)
In-Reply-To: <1368494338-7069-5-git-send-email-koverstreet@google.com>
On 05/13, Kent Overstreet wrote:
>
> +int percpu_ref_kill(struct percpu_ref *ref)
> +{
> + unsigned __percpu *pcpu_count;
> + unsigned __percpu *old;
> + unsigned count = 0;
> + int cpu;
> +
> + pcpu_count = ACCESS_ONCE(ref->pcpu_count);
> +
> + do {
> + if (!pcpu_count)
> + return 0;
> +
> + old = pcpu_count;
> + pcpu_count = cmpxchg(&ref->pcpu_count, old, NULL);
> + } while (pcpu_count != old);
This is purely cosmetic, feel free to ignore. But afaics all we
need is
pcpu_count = ACCESS_ONCE(ref->pcpu_count);
if (!cmpxchg(&ref->pcpu_count, pcpu_count, NULL))
return 0;
Oleg.
next prev parent reply other threads:[~2013-05-14 13:55 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-14 1:18 AIO refactoring/performance improvements/cancellation Kent Overstreet
2013-05-14 1:18 ` [PATCH 01/21] aio: fix kioctx not being freed after cancellation at exit time Kent Overstreet
2013-05-14 1:18 ` [PATCH 02/21] aio: reqs_active -> reqs_available Kent Overstreet
2013-05-14 1:18 ` [PATCH 03/21] aio: percpu reqs_available Kent Overstreet
2013-05-14 1:18 ` [PATCH 04/21] Generic percpu refcounting Kent Overstreet
2013-05-14 13:51 ` Oleg Nesterov [this message]
2013-05-15 8:21 ` Kent Overstreet
2013-05-14 14:59 ` Tejun Heo
2013-05-14 15:28 ` Oleg Nesterov
2013-05-15 9:00 ` Kent Overstreet
2013-05-15 8:58 ` Kent Overstreet
2013-05-15 17:37 ` Tejun Heo
2013-05-28 23:47 ` Kent Overstreet
2013-05-29 1:11 ` Tejun Heo
2013-05-29 4:59 ` Rusty Russell
2013-05-31 20:12 ` Kent Overstreet
2013-05-14 21:59 ` Tejun Heo
2013-05-14 22:15 ` Tejun Heo
2013-05-15 9:07 ` Kent Overstreet
2013-05-15 17:56 ` Tejun Heo
2013-05-16 0:26 ` Rusty Russell
2013-05-14 1:18 ` [PATCH 05/21] aio: percpu ioctx refcount Kent Overstreet
2013-05-14 1:18 ` [PATCH 06/21] aio: io_cancel() no longer returns the io_event Kent Overstreet
2013-05-14 1:18 ` [PATCH 07/21] aio: Don't use ctx->tail unnecessarily Kent Overstreet
2013-05-14 1:18 ` [PATCH 08/21] aio: Kill aio_rw_vect_retry() Kent Overstreet
2013-05-14 1:18 ` [PATCH 09/21] aio: Kill unneeded kiocb members Kent Overstreet
2013-05-14 1:18 ` [PATCH 10/21] aio: Kill ki_users Kent Overstreet
2013-05-14 1:18 ` [PATCH 11/21] aio: Kill ki_dtor Kent Overstreet
2013-05-14 1:18 ` [PATCH 12/21] aio: convert the ioctx list to radix tree Kent Overstreet
2013-05-14 1:18 ` [PATCH 13/21] block: prep work for batch completion Kent Overstreet
2013-05-14 1:18 ` [PATCH 14/21] block, aio: batch completion for bios/kiocbs Kent Overstreet
2013-05-14 1:18 ` [PATCH 15/21] virtio-blk: convert to batch completion Kent Overstreet
2013-05-14 1:18 ` [PATCH 16/21] mtip32xx: " Kent Overstreet
2013-05-14 1:18 ` [PATCH 17/21] Percpu tag allocator Kent Overstreet
2013-05-14 13:48 ` Oleg Nesterov
2013-05-14 14:24 ` Oleg Nesterov
2013-05-15 9:34 ` Kent Overstreet
2013-05-15 9:25 ` Kent Overstreet
2013-05-15 15:41 ` Oleg Nesterov
2013-05-15 16:10 ` Oleg Nesterov
2013-06-10 23:20 ` Kent Overstreet
2013-06-11 17:42 ` Oleg Nesterov
2013-05-14 15:03 ` Tejun Heo
2013-05-15 20:19 ` Andi Kleen
2013-05-14 1:18 ` [PATCH 18/21] aio: Allow cancellation without a cancel callback, new kiocb lookup Kent Overstreet
2013-05-14 1:18 ` [PATCH 19/21] aio/usb: Update cancellation for new synchonization Kent Overstreet
2013-05-14 1:18 ` [PATCH 20/21] direct-io: Set dio->io_error directly Kent Overstreet
2013-05-14 1:18 ` [PATCH 21/21] block: Bio cancellation Kent Overstreet
2013-05-15 17:52 ` Jens Axboe
2013-05-15 19:29 ` Kent Overstreet
2013-05-15 20:01 ` Jens Axboe
2013-05-31 22:52 ` Kent Overstreet
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