Gur Stavi wrote: > > Gur Stavi wrote: > > > > Gur Stavi wrote: > > > > > > Gur Stavi wrote: > > > > > > > > Gur Stavi wrote: > > > > > > > > > >> @@ -1846,21 +1846,21 @@ static int fanout_add(struct > > sock > > > > *sk, > > > > > > > > struct fanout_args *args) > > > > > > > > > >> err = -EINVAL; > > > > > > > > > >> > > > > > > > > > >> spin_lock(&po->bind_lock); > > > > > > > > > >> - if (packet_sock_flag(po, PACKET_SOCK_RUNNING) && > > > > > > > > > >> - match->type == type && > > > > > > > > > >> + if (match->type == type && > > > > > > > > > >> match->prot_hook.type == po->prot_hook.type && > > > > > > > > > >> match->prot_hook.dev == po->prot_hook.dev) { > > > > > > > > > > > > > > > > > > > > Remaining unaddressed issue is that the socket can now be > > > > added > > > > > > > > > > before being bound. See comment in v1. > > > > > > > > > > > > > > > > > > I extended the psock_fanout test with unbound fanout test. > > > > > > > > > > > > > > > > > > As far as I understand, the easiest way to verify bind is > > to > > > > test > > > > > > that > > > > > > > > > po->prot_hook.dev != NULL, since we are under a bind_lock > > > > anyway. > > > > > > > > > But perhaps a more readable and direct approach to test > > "bind" > > > > > > would be > > > > > > > > > to test po->ifindex != -1, as ifindex is commented as > > "bound > > > > > > device". > > > > > > > > > However, at the moment ifindex is not initialized to -1, I > > can > > > > add > > > > > > such > > > > > > > > > initialization, but perhaps I do not fully understand all > > the > > > > > > logic. > > > > > > > > > > > > > > > > > > Any preferences? > > > > > > > > > > > > > > > > prot_hook.dev is not necessarily set if a packet socket is > > bound. > > > > > > > > It may be bound to any device. See dev_add_pack and > > ptype_head. > > > > > > > > > > > > > > > > prot_hook.type, on the other hand, must be set if bound and > > is > > > > only > > > > > > > > modified with the bind_lock held too. > > > > > > > > > > > > > > > > Well, and in packet_create. But setsockopt PACKET_FANOUT_ADD > > also > > > > > > > > succeeds in case bind() was not called explicitly first to > > bind > > > > to > > > > > > > > a specific device or change ptype. > > > > > > > > > > > > > > Please clarify the last paragraph? When you say "also succeeds" > > do > > > > you > > > > > > > mean SHOULD succeed or MAY SUCCEED by mistake if "something" > > > > happens > > > > > > ??? > > > > > > > > > > > > I mean it succeeds currently. Which behavior must then be > > maintained. > > > > > > > > > > > > > Do you refer to the following scenario: socket is created with > > non- > > > > zero > > > > > > > protocol and becomes RUNNING "without bind" for all devices. In > > > > that > > > > > > case > > > > > > > it can be added to FANOUT without bind. Is that considered a > > bug or > > > > > > does > > > > > > > the bind requirement for fanout only apply for all-protocol (0) > > > > > > sockets? > > > > > > > > > > > > I'm beginning to think that this bind requirement is not needed. > > > > > > > > > > I agree with that. I think that is an historical mistake that > > socket > > > > > becomes implicitly bound to all interfaces if a protocol is defined > > > > > during create. Without this bind requirement would make sense. > > > > > > > > > > > > > > > > > All type and dev are valid, even if an ETH_P_NONE fanout group > > would > > > > > > be fairly useless. > > > > > > > > > > Fanout is all about RX, I think that refusing fanout for socket > > that > > > > > will not receive any packet is OK. The condition can be: > > > > > if (po->ifindex == -1 || !po->num) > > > > > > > > Fanout is not limited to sockets bound to a specific interface. > > > > This will break existing users. > > > > > > For specific interface ifindex >= 1 > > > For "any interface" ifindex == 0 > > > ifindex is -1 only if the socket was created unbound with proto == 0 > > > or for the rare race case that during re-bind the new dev became > > unlisted. > > > For both of these cases fanout should fail. > > > > The only case where packet_create does not call __register_prot_hook > > is if proto == 0. If proto is anything else, the socket will be bound, > > whether to a device hook, or ptype_all. I don't think we need this > > extra ifindex condition. > > > > Even though "unbound" is an unlikely state for such a socket the code > Should still address this state consistently. If do_bind sets ifindex > to -1 on the unlikely unlisted scenario so should packet_create on the > more likely proto == 0 scenario. do_bind sets it to -1 for unlisted probably to copy existing behavior in packet_notifier on NETDEV_DOWN. But as far as I can tell nothing that uses po->ifindex differentiates between 0 and -1. It just means that no actual device ifindex matches. > > > > > > > > Binding to ETH_P_NONE is useless, but we're not going to slow down > > > > legitimate users with branches for cases that are harmless. > > > > > > > > > > With "branch", do you refer to performance or something else? > > > As I said in other mail, ETH_P_NONE could not be used in a fanout > > > before as well because socket cannot become RUNNING with proto == 0. > > > > Good point. > > > > > For performance, we removed the RUNNING condition and added this. > > > It is not like we need to perform 5M fanout registrations/sec. It is a > > > syscall after all. > > > > It's as much about code complexity as performance. Both the patch and > > resulting code should be as small and self-evident as possible. > > > > Patch v3 introduces a lot of code churn. > > Did you look at a side by side comparison? Obviously > There is really very little > extra code. 1 file changed, 21 insertions(+), 14 deletions(-) vs 1 file changed, 5 insertions(+), 5 deletions(-) for v2. > > > > If we don't care about opening up fanout groups to ETH_P_NONE, then > > patch v2 seems sufficient. If explicitly blocking this, the ENXIO > > return can be added, but ideally without touching the other lines. > > > > I am not the one to decide if opening it is a good idea but it will be > ironic if a patch with the intention to remove the only-RUNNING > restriction will end up allowing never-RUNNING sockets into a fanout > group. It's fine to catch that, seem to just be this change? spin_lock(&po->bind_lock); - if (po->running && + if (po->num != ETH_P_NONE && match->type == type && match->prot_hook.type == po->prot_hook.type && match->prot_hook.dev == po->prot_hook.dev) {