From: David Vrabel <david.vrabel@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel@lists.xenproject.org, Keir Fraser <keir@xen.org>,
Ian Campbell <ian.campbell@citrix.com>, Tim Deegan <tim@xen.org>
Subject: Re: [PATCHv2 3/5] evtchn: use a per-event channel lock for sending events
Date: Tue, 16 Jun 2015 10:34:43 +0100 [thread overview]
Message-ID: <557FEDB3.2090601@citrix.com> (raw)
In-Reply-To: <5580060502000078000855A9@mail.emea.novell.com>
On 16/06/15 10:18, Jan Beulich wrote:
>>>> On 15.06.15 at 17:48, <david.vrabel@citrix.com> wrote:
>> @@ -609,21 +662,18 @@ int evtchn_send(struct domain *ld, unsigned int lport)
>> struct domain *rd;
>> int rport, ret = 0;
>>
>> - spin_lock(&ld->event_lock);
>> -
>> - if ( unlikely(!port_is_valid(ld, lport)) )
>> - {
>> - spin_unlock(&ld->event_lock);
>> + if ( unlikely(lport >= read_atomic(&ld->valid_evtchns)) )
>> return -EINVAL;
>> - }
>
> I don't think you really want to open code part of port_is_valid()
> (and avoid other parts of it) here? Or if really so, I think a comment
> should be added to explain it.
The ld->valid_evtchns is the only field we can safely check without
ld->event_lock.
We do check the channel state and the code that set this state uses the
full port_is_valid() call. I'll add a comment.
> And then - no change to free_xen_event_channel()?
It looked alright to me, but now I see the clear of xen_consumer needs
to be done under the channel lock. Probably by moving it to
__evtchn_close().
David
next prev parent reply other threads:[~2015-06-16 9:34 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
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 [this message]
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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