Re: [PATCH net-next 1/2] net: add IP_DSCP_MASK
From: Guillaume Nault <hidden>
Date: 2020-08-03 09:26:41
On Mon, Aug 03, 2020 at 04:02:16PM +0800, Hangbin Liu wrote:
quoted hunk ↗ jump to hunk
In RFC1349 it defined TOS field like 0 1 2 3 4 5 6 7 +-----+-----+-----+-----+-----+-----+-----+-----+ | PRECEDENCE | TOS | MBZ | +-----+-----+-----+-----+-----+-----+-----+-----+ But this has been obsoleted by RFC2474, and updated by RFC3168 later. Now the DS Field should be like 0 1 2 3 4 5 6 7 +-----+-----+-----+-----+-----+-----+-----+-----+ | DS FIELD, DSCP | ECN FIELD | +-----+-----+-----+-----+-----+-----+-----+-----+ DSCP: differentiated services codepoint ECN: Explicit Congestion Notification So the old IPTOS_TOS_MASK 0x1E should be updated. But since changed the value will break UAPI, let's add a new value IP_DSCP_MASK 0xFC as a replacement. Signed-off-by: Hangbin Liu <redacted> --- include/uapi/linux/in_route.h | 1 + include/uapi/linux/ip.h | 2 ++ 2 files changed, 3 insertions(+)diff --git a/include/uapi/linux/in_route.h b/include/uapi/linux/in_route.h index 0cc2c23b47f8..26ba4efb054d 100644 --- a/include/uapi/linux/in_route.h +++ b/include/uapi/linux/in_route.h@@ -29,5 +29,6 @@ #define RTCF_NAT (RTCF_DNAT|RTCF_SNAT) #define RT_TOS(tos) ((tos)&IPTOS_TOS_MASK) +#define RT_DSCP(tos) ((tos)&IP_DSCP_MASK) #endif /* _LINUX_IN_ROUTE_H */diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h index e42d13b55cf3..62e4169277eb 100644 --- a/include/uapi/linux/ip.h +++ b/include/uapi/linux/ip.h@@ -22,6 +22,8 @@ #define IPTOS_TOS_MASK 0x1E #define IPTOS_TOS(tos) ((tos)&IPTOS_TOS_MASK) +#define IP_DSCP_MASK 0xFC +#define IP_DSCP(tos) ((tos)&IP_DSCP_MASK)
What's the use of IP_DSCP()? It's the same as RT_DSCP(). I guess it's supposed to be the equivalent of IPTOS_TOS(), but that macro is only used once in the tree, where it could be replaced with RT_TOS(). I can't see a reason to copy this pattern.