On 11/11/2020 7:23 AM, Michael Pfeiffer wrote:
Hi,
On Tue, 2020-11-10 at 15:59 +0000, Ferruh Yigit wrote:
On 11/9/2020 2:22 PM, Michael Pfeiffer wrote:
Unlike TCP, UDP checksums are optional and may be zero to indicate "not
set" [RFC 768] (except for IPv6, where this prohibited [RFC 8200]). Add
this special case to the checksum offload emulation in net/tap.
Signed-off-by: Michael Pfeiffer <michael.pfeif...@tu-ilmenau.de>
---
drivers/net/tap/rte_eth_tap.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
index 2f8abb12c..e486b41c5 100644
--- a/drivers/net/tap/rte_eth_tap.c
+++ b/drivers/net/tap/rte_eth_tap.c
@@ -303,6 +303,7 @@ tap_verify_csum(struct rte_mbuf *mbuf)
uint16_t cksum = 0;
void *l3_hdr;
void *l4_hdr;
+ struct rte_udp_hdr *udp_hdr;
if (l2 == RTE_PTYPE_L2_ETHER_VLAN)
l2_len += 4;
@@ -349,10 +350,18 @@ tap_verify_csum(struct rte_mbuf *mbuf)
/* Don't verify checksum for multi-segment packets. */
if (mbuf->nb_segs > 1)
return;
- if (l3 == RTE_PTYPE_L3_IPV4)
+ if (l3 == RTE_PTYPE_L3_IPV4) {
+ if (l4 == RTE_PTYPE_L4_UDP) {
+ udp_hdr = (struct rte_udp_hdr *)l4_hdr;
+ if (udp_hdr->dgram_cksum == 0) {
Overall patch looks good to me, but can you please add a comment on top of
above
check to describe why checksum can be zero, as done in the commit log.
Sure, I will update the patch. I am also not completely sure whether
PKT_RX_L4_CKSUM_NONE is the right flag for this case (rather than _UNKNOWN).
From rte_core_mbuf.h:
* - PKT_RX_L4_CKSUM_UNKNOWN: no information about the RX L4 checksum
* - PKT_RX_L4_CKSUM_NONE: the L4 checksum is not correct in the packet
* data, but the integrity of the L4 data is verified.
The second part after the "but" is not really the case here. I don't know how
relevant the distinction is, as most application side code will probably only
do something like
if ((mbuf->ol_flags & PKT_RX_L4_CKSUM_MASK) == PKT_RX_L4_CKSUM_BAD)
rte_pktmbuf_free(mbuf);
anyway. Do you have any opinions on that?
I also checked for that and wasn't sure about it :) cc'ed Olivier too for
comment.
I think it is NOT 'PKT_RX_L4_CKSUM_UNKNOWN', since we know that checksum value
is 0x0000 which means it is not provided.
'PKT_RX_L4_CKSUM_NONE' suits better but not sure about the expectation on
"integrity of the L4 data is verified" part, I assume that explanation is just
to differentiate between 'CKSUM_BAD'.
