On Tue, Jan 14, 2020 at 01:24:00PM -0500, Dennis Dalessandro wrote:
> On 1/14/2020 12:00 PM, Dennis Dalessandro wrote:
> > On 1/14/2020 11:57 AM, Jason Gunthorpe wrote:
> > > On Tue, Jan 14, 2020 at 09:53:45PM +0530,
> > > madhuparnabhowmik04@xxxxxxxxx wrote:
> > > > From: Madhuparna Bhowmik <madhuparnabhowmik04@xxxxxxxxx>
> > > >
> > > > list_for_each_entry_rcu has built-in RCU and lock checking.
> > > > Pass cond argument to list_for_each_entry_rcu.
> > > >
> > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@xxxxxxxxx>
> > > > drivers/infiniband/hw/hfi1/verbs.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/infiniband/hw/hfi1/verbs.c
> > > > b/drivers/infiniband/hw/hfi1/verbs.c
> > > > index 089e201d7550..22f2d4fd2577 100644
> > > > +++ b/drivers/infiniband/hw/hfi1/verbs.c
> > > > @@ -515,7 +515,7 @@ static inline void hfi1_handle_packet(struct
> > > > hfi1_packet *packet,
> > > > opa_get_lid(packet->dlid, 9B));
> > > > if (!mcast)
> > > > goto drop;
> > > > - list_for_each_entry_rcu(p, &mcast->qp_list, list) {
> > > > + list_for_each_entry_rcu(p, &mcast->qp_list, list,
> > > > lockdep_is_held(&(ibp->rvp.lock))) {
> > >
> > > Okay, this looks reasonable
> > >
> > > Mike, Dennis, is this the right lock to test?
> > >
> >
> > I'm looking at that right now actually, I don't think this is correct.
> > Wanted to talk to Mike before I send a response though.
> >
> > -Denny
>
> That's definitely going to throw a ton of lock dep messages. It's not really
> the right lock either. Instead what we probably need to do is what we do in
> the non-multicast part of the code and take the rcu_read_lock().
Uh.. why is this using the _rcu varient without holding the rcu lock?
That is quite wrong already.
Jason
