[INET]: Add IP(V6)_PMTUDISC_RPOBE

Add IP(V6)_PMTUDISC_PROBE value for IP(V6)_MTU_DISCOVER.  This option forces
us not to fragment, but does not make use of the kernel path MTU discovery.
That is, it allows for user-mode MTU probing (or, packetization-layer path
MTU discovery).  This is particularly useful for diagnostic utilities, like
traceroute/tracepath.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index c199d2311731..4d544573f48a 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -542,7 +542,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
                 inet->hdrincl = val ? 1 : 0;
                 break;
         case IP_MTU_DISCOVER:
-                if (val<0 || val>2)
+                if (val<0 || val>3)
                         goto e_inval;
                 inet->pmtudisc = val;
                 break;