[RFC] mbuf: outer offsets must be zero for non-tunnel packets

Message ID 20190412150542.12026-1-ivan.malov@oktetlabs.ru
State Superseded
Delegated to: Thomas Monjalon
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Series
  • [RFC] mbuf: outer offsets must be zero for non-tunnel packets
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Checks

Context Check Description
ci/Intel-compilation success Compilation OK
ci/checkpatch success coding style OK

Commit Message

Ivan Malov April 12, 2019, 3:05 p.m.
Make sure that outer L2 and L3 header length fields are
equal to zero for non-tunnel packets in order to ensure
consistent and predictable behaviour in network drivers.
Explain this expectation in comments to help developers.

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
---

Notes:
    At the time of writing a couple of network drivers rely on
    the statement (i40e, ice) whilst more drivers have runtime
    conditional checks to guard all references to these fields.
    This patch is likely to relieve datapath checks in drivers.

 lib/librte_mbuf/rte_mbuf.h | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Patch

diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index f7886dc..9d316ef 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -696,7 +696,12 @@  struct rte_mbuf {
 			uint64_t tso_segsz:RTE_MBUF_TSO_SEGSZ_BITS;
 			/**< TCP TSO segment size */
 
-			/* fields for TX offloading of tunnels */
+			/*
+			 * Fields for Tx offloading of tunnels.
+			 * These fields must be equal to zero in the case
+			 * when (ol_flags & PKT_TX_TUNNEL_MASK) == 0,
+			 * i.e. for all non-tunnel packets.
+			 */
 			uint64_t outer_l3_len:RTE_MBUF_OUTL3_LEN_BITS;
 			/**< Outer L3 (IP) Hdr Length. */
 			uint64_t outer_l2_len:RTE_MBUF_OUTL2_LEN_BITS;
@@ -2370,6 +2375,11 @@  static inline int rte_pktmbuf_chain(struct rte_mbuf *head, struct rte_mbuf *tail
 			!(ol_flags & PKT_TX_OUTER_IPV4))
 		return -EINVAL;
 
+	/* Outer L2/L3 offsets must be equal to zero for non-tunnel packets. */
+	if ((ol_flags & PKT_TX_TUNNEL_MASK) == 0 &&
+	    m->outer_l2_len + m->outer_l3_len != 0)
+		return -EINVAL;
+
 	return 0;
 }