On 06/06/2013 03:23 PM, Michael S. Tsirkin wrote: > On Thu, Jun 06, 2013 at 11:16:51AM +0800, Jason Wang wrote: >> > On 06/05/2013 06:59 PM, Michael S. Tsirkin wrote: >>> > > On Wed, Jun 05, 2013 at 02:36:31PM +0800, Jason Wang wrote: >>>> > >> This patch adds TUNSETQUEUE ioctl to let userspace can temporarily >>>> > >> disable or >>>> > >> enable a queue of macvtap. This is used to be compatible at API layer >>>> > >> of tuntap >>>> > >> to simplify the userspace to manage the queues. This is done through >>>> > >> introducing >>>> > >> a linked list to track all taps while using vlan->taps array to only >>>> > >> track >>>> > >> active taps. >>>> > >> >>>> > >> Signed-off-by: Jason Wang <jasow...@redhat.com> >>>> > >> --- >>>> > >> drivers/net/macvtap.c | 133 >>>> > >> +++++++++++++++++++++++++++++++++++++++----- >>>> > >> include/linux/if_macvlan.h | 4 + >>>> > >> 2 files changed, 122 insertions(+), 15 deletions(-) >>>> > >> >>>> > >> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c >>>> > >> index 14764cc..355e6ad 100644 >>>> > >> --- a/drivers/net/macvtap.c >>>> > >> +++ b/drivers/net/macvtap.c
[...] >>>> >>> > > >>>> > >> since we are protected by rcu read lock, >>>> > >> + * we're safe here. >>> > > I don't really understand what is this comment trying to say. >>> > > What is protected? What is safe? safe time as what? >> > >> > Will make it clear as: >> > >> > "numvtaps is just a hint, even if the number of active taps were reduced >> > in the same tap, since the tap pointers were protected by rcu read lock, >> > they are safe even if some of them were being removed" > I think I see. I think what you really meant is two things: > - near macvtap_forward: > /* called under rcu read lock */ > - and here: > /* > * Access to taps array is protected by rcu, but access to numvtaps > * isn't. Below we use it to lookup a queue, but treat it as a hint > * and validate that the result isn't NULL - in case we are > * racing against queue removal. > */ Yes, will correct the comments. Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
