From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [PATCHv2 3/5] evtchn: use a per-event channel lock for sending events Date: Tue, 16 Jun 2015 10:18:29 +0100 Message-ID: <5580060502000078000855A9@mail.emea.novell.com> References: <1434383299-21833-1-git-send-email-david.vrabel@citrix.com> <1434383299-21833-4-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Z4n0r-0007GM-BF for xen-devel@lists.xenproject.org; Tue, 16 Jun 2015 09:18:33 +0000 In-Reply-To: <1434383299-21833-4-git-send-email-david.vrabel@citrix.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel Cc: xen-devel@lists.xenproject.org, Keir Fraser , Ian Campbell , Tim Deegan List-Id: xen-devel@lists.xenproject.org >>> On 15.06.15 at 17:48, 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. > @@ -1163,11 +1213,15 @@ int alloc_unbound_xen_event_channel( > if ( rc ) > goto out; > > + spin_lock(&chn->lock); > + > chn->state = ECS_UNBOUND; > chn->xen_consumer = get_xen_consumer(notification_fn); > chn->notify_vcpu_id = lvcpu; > chn->u.unbound.remote_domid = remote_domid; > > + spin_unlock(&chn->lock); > + > out: > spin_unlock(&ld->event_lock); I don't see why you shouldn't be able to move up this unlock. And then - no change to free_xen_event_channel()? > @@ -1214,6 +1268,8 @@ void notify_via_xen_event_channel(struct domain *ld, int lport) > lchn = evtchn_from_port(ld, lport); > ASSERT(consumer_is_xen(lchn)); > > + spin_lock(&lchn->lock); > + > if ( likely(lchn->state == ECS_INTERDOMAIN) ) > { > rd = lchn->u.interdomain.remote_dom; > @@ -1221,6 +1277,8 @@ void notify_via_xen_event_channel(struct domain *ld, int lport) > evtchn_port_set_pending(rd, rchn->notify_vcpu_id, rchn); > } > > + spin_unlock(&lchn->lock); > + > spin_unlock(&ld->event_lock); > } Again I think the event lock can be dropped earlier now. Jan