On Fri, Sep 2, 2016 at 11:13 AM, Brenden Blanco <bbla...@plumgrid.com> wrote: > On Mon, Aug 29, 2016 at 10:46:38AM -0700, Tom Herbert wrote: > [...] >> Brenden, tracking down how the structure is freed needed a few steps, >> please make sure the RCU requirements are well documented. Also, I'm > Really? It's just bpf_prog_put->call_rcu(__bpf_prog_put_rcu). I suppose > what's missing is a general guideline for which functions new consumers > of bpf should use, but I wouldn't trust myself to write such holistic > documentation accurately (e.g. interacting with nmi probes and such). >> still not a fan of using xchg to set the program, seems that a lock >> could be used in that path. > Where would such a lock go? Everything in mlx4/en_netdev.c relies on > rtnl, which seems sufficient and obvious...adding some new field > specific lock would be distracting and unneeded.
Just use the same mutex_lock that is already being taken in case when priv->xdp_ring_num != xdp_ring_num. Then use normal rcu functions to dereference and assign pointers. Tom >> >> Thanks, >> Tom
