On Wed, 2016-08-31 at 18:00 +0200, Sebastian Andrzej Siewior wrote: > It looks like the this_cpu_ptr() access in icmp_sk() is protected with > local_bh_disable(). To avoid missing serialization in -RT I am adding > here a local lock. No crash has been observed, this is just precaution. >
Hmm... > Signed-off-by: Sebastian Andrzej Siewior <[email protected]> > --- > net/ipv4/icmp.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c > index c1f1d5030d37..63731fd6af3e 100644 > --- a/net/ipv4/icmp.c > +++ b/net/ipv4/icmp.c > @@ -78,6 +78,7 @@ > #include <linux/string.h> > #include <linux/netfilter_ipv4.h> > #include <linux/slab.h> > +#include <linux/locallock.h> > #include <net/snmp.h> > #include <net/ip.h> > #include <net/route.h> > @@ -205,6 +206,8 @@ static const struct icmp_control > icmp_pointers[NR_ICMP_TYPES+1]; > * > * On SMP we have one ICMP socket per-cpu. > */ > +static DEFINE_LOCAL_IRQ_LOCK(icmp_sk_lock); > + > static struct sock *icmp_sk(struct net *net) > { > return *this_cpu_ptr(net->ipv4.icmp_sk); > @@ -216,12 +219,14 @@ static inline struct sock *icmp_xmit_lock(struct net > *net) > > local_bh_disable(); > > + local_lock(icmp_sk_lock); Deadlock alert ? Please read the comment few lines after, explaining why we have to use spin_trylock(). Or maybe I should double check what is local_lock() in RT > sk = icmp_sk(net); > > if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { ... > /* This can happen if the output path signals a > * dst_link_failure() for an outgoing ICMP packet. > */ > + local_unlock(icmp_sk_lock); > local_bh_enable(); > return NULL;
