On 28 Jun 2018, at 17:41, Tiago Lam wrote:
When a dp_packet is from a DPDK source, and it contains multi-segment
mbufs, the data_len is not equal to the packet size, pkt_len. Instead,
the data_len of each mbuf in the chain should be considered while
distributing the new (provided) size.
To account for the above dp_packet_set_size() has been changed so
that,
in the multi-segment mbufs case, only the data_len on the last mbuf of
the chain and the total size of the packet, pkt_len, are changed. The
data_len on the intermediate mbufs preceeding the last mbuf is not
changed by dp_packet_set_size(). Furthermore, in some cases
dp_packet_set_size() may be used to set a smaller size than the
current
packet size, thus effectively trimming the end of the packet. In the
multi-segment mbufs case this may lead to lingering mbufs that may
need
freeing.
__dp_packet_set_data() now also updates an mbufs' data_len after
setting
the data offset. This is so that both fields are always in sync for
each
mbuf in a chain.
Co-authored-by: Michael Qiu <[email protected]>
Co-authored-by: Mark Kavanagh <[email protected]>
Co-authored-by: Przemyslaw Lal <[email protected]>
Co-authored-by: Marcin Ksiadz <[email protected]>
Co-authored-by: Yuanhan Liu <[email protected]>
Signed-off-by: Michael Qiu <[email protected]>
Signed-off-by: Mark Kavanagh <[email protected]>
Signed-off-by: Przemyslaw Lal <[email protected]>
Signed-off-by: Marcin Ksiadz <[email protected]>
Signed-off-by: Yuanhan Liu <[email protected]>
Signed-off-by: Tiago Lam <[email protected]>
---
lib/dp-packet.h | 67
++++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 55 insertions(+), 12 deletions(-)
diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index c612ad4..d8cd35c 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -429,17 +429,44 @@ dp_packet_size(const struct dp_packet *b)
static inline void
dp_packet_set_size(struct dp_packet *b, uint32_t v)
{
- /* netdev-dpdk does not currently support segmentation;
consequently, for
- * all intents and purposes, 'data_len' (16 bit) and 'pkt_len'
(32 bit) may
- * be used interchangably.
- *
- * On the datapath, it is expected that the size of packets
- * (and thus 'v') will always be <= UINT16_MAX; this means that
there is no
- * loss of accuracy in assigning 'v' to 'data_len'.
- */
- b->mbuf.data_len = (uint16_t)v; /* Current seg length. */
- b->mbuf.pkt_len = v; /* Total length of all segments
linked to
- * this segment. */
+ if (b->source == DPBUF_DPDK) {
+ struct rte_mbuf *mbuf = &b->mbuf;
+ struct rte_mbuf *fmbuf = mbuf;
+ uint16_t new_len = v;
+ uint16_t data_len;
+ uint16_t nb_segs = 0;
+ uint16_t pkt_len = 0;
+
+ /* Trim 'v' length bytes from the end of the chained buffers,
freeing
+ any buffers that may be left floating */
+ while (mbuf) {
+ data_len = MIN(new_len, mbuf->data_len);
+ mbuf->data_len = data_len;
+
+ if (new_len - data_len <= 0) {
+ /* Free the rest of chained mbufs */
+ free_dpdk_buf(CONTAINER_OF(mbuf->next, struct
dp_packet,
+ mbuf));
+ mbuf->next = NULL;
+ } else if (!mbuf->next) {
+ /* Don't assign more than what we have available */
+ mbuf->data_len = MIN(new_len,
+ mbuf->buf_len - mbuf->data_off);
+ }
+
+ new_len -= data_len;
+ nb_segs += 1;
+ pkt_len += mbuf->data_len;
+ mbuf = mbuf->next;
+ }
+
+ fmbuf->nb_segs = nb_segs;
+ fmbuf->pkt_len = pkt_len;
Guess we do not need the extra variable, we can just do b->mbuf.pkt_len
etc as below. Looks like a left over from the previous revision?
In the increase packet size case we can end up with an b->mbuf.pkt_len <
v, maybe we should assert on this?
+ } else {
+ b->mbuf.data_len = v;
+ /* Total length of all segments linked to this segment. */
+ b->mbuf.pkt_len = v;
+ }
}
static inline uint16_t
@@ -451,7 +478,23 @@ __packet_data(const struct dp_packet *b)
static inline void
__packet_set_data(struct dp_packet *b, uint16_t v)
{
- b->mbuf.data_off = v;
+ if (b->source == DPBUF_DPDK) {
+ uint16_t prev_ofs = b->mbuf.data_off;
+ b->mbuf.data_off = v;
+ int16_t ofs_diff = prev_ofs - b->mbuf.data_off;
+
+ /* When dealing with DPDK mbufs, keep data_off and data_len
in sync.
+ * Thus, update data_len if the length changes with the move
of
+ * data_off. However, if data_len is 0, there's no data to
move and
+ * data_Len should remain 0. */
+
What if the data offset moves to the second buffer? This would probably
never happen as all APIs assume a single address space (and they seem to
calculate the offset like this), but an assert might help to avoid
problems in the future.
+ if (b->mbuf.data_len != 0) {
+ b->mbuf.data_len = MIN(b->mbuf.data_len + ofs_diff,
+ b->mbuf.buf_len -
b->mbuf.data_off);
+ }
+ } else {
+ b->mbuf.data_off = v;
+ }
}
static inline uint16_t
--
2.7.4
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