From: Ian Campbell <ian.campbell@citrix.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: xen-devel@lists.xenproject.org, Keir Fraser <keir@xen.org>,
Tim Deegan <tim@xen.org>, Jan Beulich <jbeulich@suse.com>
Subject: Re: [PATCHv2 2/5] evtchn: simplify port_is_valid()
Date: Mon, 15 Jun 2015 16:57:46 +0100 [thread overview]
Message-ID: <1434383866.13744.28.camel@citrix.com> (raw)
In-Reply-To: <1434383299-21833-3-git-send-email-david.vrabel@citrix.com>
On Mon, 2015-06-15 at 16:48 +0100, David Vrabel wrote:
> By keeping a count of the number of currently valid event channels,
> port_is_valid() can be simplified.
>
> d->valid_evtchns can also be tested without holding d->event_lock which
> will be useful later on.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
> v2:
> - Used unsigned int for d->valid_evtchns.
> ---
> xen/common/event_channel.c | 3 +++
> xen/include/xen/event.h | 4 +---
> xen/include/xen/sched.h | 5 +++--
> 3 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
> index 947880f..fd48646 100644
> --- a/xen/common/event_channel.c
> +++ b/xen/common/event_channel.c
> @@ -189,6 +189,8 @@ static int get_free_port(struct domain *d)
> return -ENOMEM;
> bucket_from_port(d, port) = chn;
>
> + write_atomic(&d->valid_evtchns, d->valid_evtchns + EVTCHNS_PER_BUCKET);
Shouldn't this be atomic_add? Otherwise the result of what you have here
is actually a non-atomic read/add/write.
Ian.
next prev parent reply other threads:[~2015-06-15 16:57 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 15:48 [PATCHv2 0/5] evtchn: Improve scalebility David Vrabel
2015-06-15 15:48 ` [PATCHv2 1/5] evtchn: factor out freeing an event channel David Vrabel
2015-06-15 15:48 ` [PATCHv2 2/5] evtchn: simplify port_is_valid() David Vrabel
2015-06-15 15:57 ` Ian Campbell [this message]
2015-06-15 15:59 ` David Vrabel
2015-06-15 16:09 ` Ian Campbell
2015-06-15 15:48 ` [PATCHv2 3/5] evtchn: use a per-event channel lock for sending events David Vrabel
2015-06-16 9:18 ` Jan Beulich
2015-06-16 9:34 ` David Vrabel
2015-06-16 9:51 ` Jan Beulich
2015-06-16 9:57 ` David Vrabel
2015-06-16 15:19 ` David Vrabel
2015-06-16 15:58 ` David Vrabel
2015-06-16 16:19 ` Jan Beulich
2015-06-16 16:39 ` David Vrabel
2015-06-17 7:05 ` Jan Beulich
2015-06-16 16:06 ` Jan Beulich
2015-06-15 15:48 ` [PATCHv2 4/5] evtchn: remove the locking when unmasking an event channel David Vrabel
2015-06-16 9:19 ` Jan Beulich
2015-06-16 9:40 ` David Vrabel
2015-06-15 15:48 ` [PATCHv2 5/5] evtchn: pad struct evtchn to 64 bytes David Vrabel
2015-06-16 9:22 ` Jan Beulich
2015-06-16 11:14 ` Julien Grall
2015-06-16 11:59 ` Jan Beulich
2015-06-16 12:57 ` Julien Grall
2015-06-16 13:13 ` David Vrabel
2015-06-16 13:27 ` Julien Grall
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