[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCHv2 2/5] evtchn: simplify port_is_valid()
On Mon, 2015-06-15 at 16:59 +0100, David Vrabel wrote: > On 15/06/15 16:57, Ian Campbell wrote: > > 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@xxxxxxxxxx> > >> --- > >> 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. > > This field is only updated while holding d->event_lock. Only reads are > unlocked. Oh good, thanks! Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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