Oliver, On di, 21 jan 2020 21:03:42 +0100, Oliver Hartkopp wrote: > Hi Kurt, > > On 21/01/2020 20.22, Kurt Van Dijck wrote: > > >I decreased the CC list a bit, as I'm more like thinking in the wild > >now: > > Good choice! > > >Since the problems happens only rarely, and with vxcan, I assume not > >vcan, I started to think to locking issues. > > > >1. What surprised me a bit is 'rtnl_dereference()' calls, without > >rcu_read_lock() around it? is that supposed to be ok? > > Don't know. This code was just copied from veth.c > > But veth doesn't fiddle with ml_priv like us. > > >2. is it possible to call vxcan_dellink in between the 2 > >rcu_assign_pointer() calls in vxcan_newlink(), resulting in a dead end, > >i.e. one end is referenced, but already deleted? > >I'd expect a kind of rcu_write_lock around the cross-linking at least. > > Will look into this too. When there's a comment this might be a > justification for doing "hacky" things ;-) Maybe move the crosslinking to before the register, then they're inaccessible from userspace. and a little comment, indeed. Kurt
