On 4/20/22 5:21 PM, Guillaume Nault wrote: > All callers already initialise ->flowi4_scope with RT_SCOPE_UNIVERSE, > either by manual field assignment, memset(0) of the whole structure or > implicit structure initialisation of on-stack variables > (RT_SCOPE_UNIVERSE actually equals 0). > > Therefore, we don't need to always initialise ->flowi4_scope in > ip_rt_fix_tos(). We only need to reduce the scope to RT_SCOPE_LINK when > the special RTO_ONLINK flag is present in the tos. > > This will allow some code simplification, like removing > ip_rt_fix_tos(). Also, the long term idea is to remove RTO_ONLINK > entirely by properly initialising ->flowi4_scope, instead of > overloading ->flowi4_tos with a special flag. Eventually, this will > allow to convert ->flowi4_tos to dscp_t. > > Signed-off-by: Guillaume Nault <gnault@xxxxxxxxxx> > --- > It's important for the correctness of this patch that all callers > initialise ->flowi4_scope to 0 (in one way or another). Auditing all of > them is long, although each case is pretty trivial. > > If it helps, I can send a patch series that converts implicit > initialisation of ->flowi4_scope with an explicit assignment to > RT_SCOPE_UNIVERSE. This would also have the advantage of making it > clear to future readers that ->flowi4_scope _has_ to be initialised. I > haven't sent such patch series to not overwhelm reviewers with trivial > and not technically-required changes (there are 40+ places to modify, > scattered over 30+ different files). But if anyone prefers explicit > initialisation everywhere, then just let me know and I'll send such > patches. There are a handful of places that open code the initialization of the flow struct. I *think* I found all of them in 40867d74c374. > --- > net/ipv4/route.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c > index e839d424b861..d8f82c0ac132 100644 > --- a/net/ipv4/route.c > +++ b/net/ipv4/route.c > @@ -503,8 +503,8 @@ static void ip_rt_fix_tos(struct flowi4 *fl4) > __u8 tos = RT_FL_TOS(fl4); > > fl4->flowi4_tos = tos & IPTOS_RT_MASK; > - fl4->flowi4_scope = tos & RTO_ONLINK ? > - RT_SCOPE_LINK : RT_SCOPE_UNIVERSE; > + if (tos & RTO_ONLINK) > + fl4->flowi4_scope = RT_SCOPE_LINK; > } > > static void __build_flow_key(const struct net *net, struct flowi4 *fl4, Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
