| Message ID | 1349609168-9848-4-git-send-email-ja@ssi.bg |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Sun, 2012-10-07 at 14:26 +0300, Julian Anastasov wrote: > Avoid NULL ptr dereference and caching if > nh_pcpu_rth_output is not allocated. > > Signed-off-by: Julian Anastasov <ja@ssi.bg> > --- > net/ipv4/route.c | 12 +++++++++--- > 1 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c > index 488a8bb..0a600cc 100644 > --- a/net/ipv4/route.c > +++ b/net/ipv4/route.c > @@ -1798,18 +1798,24 @@ static struct rtable *__mkroute_output(const struct fib_result *res, > fnhe = NULL; > if (fi) { > struct rtable __rcu **prth; > + struct fib_nh *nh = &FIB_RES_NH(*res); > > - fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr); > + fnhe = find_exception(nh, fl4->daddr); > if (fnhe) > prth = &fnhe->fnhe_rth; > - else > - prth = __this_cpu_ptr(FIB_RES_NH(*res).nh_pcpu_rth_output); > + else { > + if (!nh->nh_pcpu_rth_output) > + goto add; > + prth = __this_cpu_ptr(nh->nh_pcpu_rth_output); > + } > rth = rcu_dereference(*prth); > if (rt_cache_valid(rth)) { > dst_hold(&rth->dst); > return rth; > } > } > + > +add: > rth = rt_dst_alloc(dev_out, > IN_DEV_CONF_GET(in_dev, NOPOLICY), > IN_DEV_CONF_GET(in_dev, NOXFRM), Alternative would be to make sure the allocation succeeded in fib_create_info(), but I have no idea on the maximal number of fib_info a complex routing setup might need ? I guess a typical machine needs less than 30 fib_info... -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello, On Sun, 7 Oct 2012, Eric Dumazet wrote: > On Sun, 2012-10-07 at 14:26 +0300, Julian Anastasov wrote: > > Avoid NULL ptr dereference and caching if > > nh_pcpu_rth_output is not allocated. > > > > Signed-off-by: Julian Anastasov <ja@ssi.bg> > > --- > > net/ipv4/route.c | 12 +++++++++--- > > 1 files changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c > > index 488a8bb..0a600cc 100644 > > --- a/net/ipv4/route.c > > +++ b/net/ipv4/route.c > > @@ -1798,18 +1798,24 @@ static struct rtable *__mkroute_output(const struct fib_result *res, > > fnhe = NULL; > > if (fi) { > > struct rtable __rcu **prth; > > + struct fib_nh *nh = &FIB_RES_NH(*res); > > > > - fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr); > > + fnhe = find_exception(nh, fl4->daddr); > > if (fnhe) > > prth = &fnhe->fnhe_rth; > > - else > > - prth = __this_cpu_ptr(FIB_RES_NH(*res).nh_pcpu_rth_output); > > + else { > > + if (!nh->nh_pcpu_rth_output) > > + goto add; > > + prth = __this_cpu_ptr(nh->nh_pcpu_rth_output); > > + } > > rth = rcu_dereference(*prth); > > if (rt_cache_valid(rth)) { > > dst_hold(&rth->dst); > > return rth; > > } > > } > > + > > +add: > > rth = rt_dst_alloc(dev_out, > > IN_DEV_CONF_GET(in_dev, NOPOLICY), > > IN_DEV_CONF_GET(in_dev, NOXFRM), > > Alternative would be to make sure the allocation succeeded in > fib_create_info(), but I have no idea on the maximal number of fib_info > a complex routing setup might need ? I too preferred not to touch there because I don't know how much we can want from alloc_percpu. > I guess a typical machine needs less than 30 fib_info... May be, I guess it all depends on the present primary addresses, gateways and devices. Thousands of routes do not look so scary because they will use small number of fib_infos. But it is a problem that we allocate memory that may never be used, there is no chance to expire it. Not sure how good is the idea to create fib_infos without percpu allocations and the first traffic to notify some thread to attach such arrays? We can safe memory if the local/broadcast fib_infos are not used for output routes. But such idea will cost many checks in fast path. Another hack could be to use 1 entry for local/broadcast/mcast and array for unicast. Type RTN_BROADCAST is actually not cached at all, so we do not need to allocate array. Regards -- Julian Anastasov <ja@ssi.bg> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Julian Anastasov <ja@ssi.bg> Date: Sun, 7 Oct 2012 14:26:05 +0300 > Avoid NULL ptr dereference and caching if > nh_pcpu_rth_output is not allocated. > > Signed-off-by: Julian Anastasov <ja@ssi.bg> Ugh. Checking for alloc_percpu() failures in fib_create_info() is 1,000 times better than doing stuff like this in the fast path. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 488a8bb..0a600cc 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1798,18 +1798,24 @@ static struct rtable *__mkroute_output(const struct fib_result *res, fnhe = NULL; if (fi) { struct rtable __rcu **prth; + struct fib_nh *nh = &FIB_RES_NH(*res); - fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr); + fnhe = find_exception(nh, fl4->daddr); if (fnhe) prth = &fnhe->fnhe_rth; - else - prth = __this_cpu_ptr(FIB_RES_NH(*res).nh_pcpu_rth_output); + else { + if (!nh->nh_pcpu_rth_output) + goto add; + prth = __this_cpu_ptr(nh->nh_pcpu_rth_output); + } rth = rcu_dereference(*prth); if (rt_cache_valid(rth)) { dst_hold(&rth->dst); return rth; } } + +add: rth = rt_dst_alloc(dev_out, IN_DEV_CONF_GET(in_dev, NOPOLICY), IN_DEV_CONF_GET(in_dev, NOXFRM),
Avoid NULL ptr dereference and caching if nh_pcpu_rth_output is not allocated. Signed-off-by: Julian Anastasov <ja@ssi.bg> --- net/ipv4/route.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-)