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inet_ecn: Use csum16_add() helper for IP_ECN_set_* helpers

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Jakub pointed out that the IP_ECN_set* helpers basically open-code
csum16_add(), so let's switch them over to using the helper instead.

v2:
- Use __be16 for check_add stack variable in IP_ECN_set_ce() (kbot)
v3:
- Turns out we need __force casts to do arithmetic on __be16 types

Reported-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Jonathan Morton <chromatix99@gmail.com>
Tested-by: Pete Heist <pete@heistp.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20201211142638.154780-1-toke@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Toke Høiland-Jørgensen 2020-12-11 15:26:38 +01:00 • committed by Jakub Kicinski
parent 989a1db06e
commit 0780b41456
1 changed files with 6 additions and 8 deletions
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14
include/net/inet_ecn.h
View file

@ -8,6 +8,7 @@
#include <net/inet_sock.h>
#include <net/dsfield.h>
#include <net/checksum.h>
enum {
INET_ECN_NOT_ECT = 0,
@ -75,8 +76,8 @@ static inline void INET_ECN_dontxmit(struct sock *sk)
static inline int IP_ECN_set_ce(struct iphdr *iph)
{
u32 check = (__force u32)iph->check;
u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
__be16 check_add;
/*
* After the last operation we have (in binary):
@ -93,23 +94,20 @@ static inline int IP_ECN_set_ce(struct iphdr *iph)
* INET_ECN_ECT_1 => check += htons(0xFFFD)
* INET_ECN_ECT_0 => check += htons(0xFFFE)
*/
check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
check_add = (__force __be16)((__force u16)htons(0xFFFB) +
(__force u16)htons(ecn));
iph->check = (__force __sum16)(check + (check>=0xFFFF));
iph->check = csum16_add(iph->check, check_add);
iph->tos |= INET_ECN_CE;
return 1;
}
static inline int IP_ECN_set_ect1(struct iphdr *iph)
{
u32 check = (__force u32)iph->check;
if ((iph->tos & INET_ECN_MASK) != INET_ECN_ECT_0)
return 0;
check += (__force u16)htons(0x1);
iph->check = (__force __sum16)(check + (check>=0xFFFF));
iph->check = csum16_add(iph->check, htons(0x1));
iph->tos ^= INET_ECN_MASK;
return 1;
}