On 16-08-29 02:20 PM, Eric Dumazet wrote:
You would need to store everything in an object, managed by rcu.
struct my_rcu_safe_struct {
u32 flags;
u8 eth_dst[ETH_ALEN];
u8 eth_src[ETH_ALEN];
__be16 eth_type;
};
And then allocate a new one when you need to update the infos (from
tcf_skbmod_init(())
RCU : Read Copy Update.
Then in the reader you would use
rcu_read_lock();
myptr = rcu_dereference(d->ptr);
if (myptr) {
if (myptr->flags & SKBMOD_F_DMAC)
ether_addr_copy(eth_hdr(skb)->h_dest, myptr->eth_dst);
if (myptr->flags & SKBMOD_F_SMAC)
ether_addr_copy(eth_hdr(skb)->h_source, myptr->eth_src);
if (myptr->flags & SKBMOD_F_ETYPE)
eth_hdr(skb)->h_proto = myptr->eth_type;
}
rcu_read_unlock();
Thanks Eric.
This is the approach i thought Cong was going to take but in a way that
it applies to all actions.
It requires I do this extra allocation per update/create - I am not sure
how much of a big deal that is (we take pride in our update rate).
Let me work and post something simple that captures these ideas
then wait to see what Cong has in mind for the general approach.
cheers,
jamal
