In its current implementation dp_packet_shift() is also unaware of
multi-seg mbufs (that holds data in memory non-contiguously) and assumes
that data exists contiguously in memory, memmove'ing data to perform the
shift.
To add support for multi-seg mbuds a new set of functions was
introduced, dp_packet_mbuf_shift() and dp_packet_mbuf_write(). These
functions are used by dp_packet_shift(), when handling multi-seg mbufs,
to shift and write data within a chain of mbufs.
Signed-off-by: Tiago Lam <tiago....@intel.com>
Acked-by: Eelco Chaudron <echau...@redhat.com>
---
lib/dp-packet.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
lib/dp-packet.h | 10 ++++++
2 files changed, 107 insertions(+)
diff --git a/lib/dp-packet.c b/lib/dp-packet.c
index 2aaeaae..d6e19eb 100644
--- a/lib/dp-packet.c
+++ b/lib/dp-packet.c
@@ -294,6 +294,97 @@ dp_packet_prealloc_headroom(struct dp_packet *b, size_t
size)
}
}
+#ifdef DPDK_NETDEV
+/* Write len data bytes in a mbuf at specified offset.
+ *
+ * 'mbuf', pointer to the destination mbuf where 'ofs' is, and the mbuf where
+ * the data will first be written.
+ * 'ofs', the offset within the provided 'mbuf' where 'data' is to be written.
+ * 'len', the size of the to be written 'data'.
+ * 'data', pointer to the to be written bytes.
+ *
+ * XXX: This function is the counterpart of the `rte_pktmbuf_read()` function
+ * available with DPDK, in the rte_mbuf.h */
+void
+dp_packet_mbuf_write(struct rte_mbuf *mbuf, int16_t ofs, uint32_t len,
+ const void *data)
+{
+ char *dst_addr;
+ uint16_t data_len;
+ int len_copy;
+ while (mbuf) {
+ if (len == 0) {
+ break;
+ }
+
+ dst_addr = rte_pktmbuf_mtod_offset(mbuf, char *, ofs);
+ data_len = MBUF_BUF_END(mbuf->buf_addr, mbuf->buf_len) - dst_addr;
+
+ len_copy = MIN(len, data_len);
+ /* We don't know if 'data' is the result of a rte_pktmbuf_read() call,
+ * in which case we may end up writing to the same region of memory we
+ * are reading from and overlapping. Hence the use of memmove() here */
+ memmove(dst_addr, data, len_copy);
+
+ data = ((char *) data) + len_copy;
+ len -= len_copy;
+ ofs = 0;
+
+ mbuf = mbuf->next;
+ }
+}
+
+static void
+dp_packet_mbuf_shift_(struct rte_mbuf *dbuf, int16_t dst_ofs,
+ const struct rte_mbuf *sbuf, uint16_t src_ofs, int len)
+{
+ char rd[len];
+ const char *wd = rte_pktmbuf_read(sbuf, src_ofs, len, rd);
+
+ ovs_assert(wd);
+
+ dp_packet_mbuf_write(dbuf, dst_ofs, len, wd);
+}
+
+/* Similarly to dp_packet_shift(), shifts the data within the mbufs of a
+ * dp_packet of DPBUF_DPDK source by 'delta' bytes.
+ * Caller must make sure of the following conditions:
+ * - When shifting left, delta can't be bigger than the data_len available in
+ * the last mbuf;
+ * - When shifting right, delta can't be bigger than the space available in the
+ * first mbuf (buf_len - data_off).
+ * Both these conditions guarantee that a shift operation doesn't fall outside
+ * the bounds of the existing mbufs, so that the first and last mbufs (when
+ * using multi-segment mbufs), remain the same. */
+static void
+dp_packet_mbuf_shift(struct dp_packet *b, int delta)
+{
+ uint16_t src_ofs;
+ int16_t dst_ofs;
+
+ struct rte_mbuf *mbuf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+ struct rte_mbuf *tmbuf = rte_pktmbuf_lastseg(mbuf);
+
+ if (delta < 0) {
+ ovs_assert(-delta <= tmbuf->data_len);
+ } else {
+ ovs_assert(delta < (mbuf->buf_len - mbuf->data_off));
+ }
+
+ /* Set the destination and source offsets to copy to */
+ dst_ofs = delta;
+ src_ofs = 0;
+
+ /* Shift data from src mbuf and offset to dst mbuf and offset */
+ dp_packet_mbuf_shift_(mbuf, dst_ofs, mbuf, src_ofs,
+ rte_pktmbuf_pkt_len(mbuf));
+
+ /* Update mbufs' properties, and if using multi-segment mbufs, first and
+ * last mbuf's data_len also needs to be adjusted */
+ mbuf->data_off = mbuf->data_off + dst_ofs;
+}
+#endif
+
/* Shifts all of the data within the allocated space in 'b' by 'delta' bytes.
* For example, a 'delta' of 1 would cause each byte of data to move one byte
* forward (from address 'p' to 'p+1'), and a 'delta' of -1 would cause each
@@ -306,6 +397,12 @@ dp_packet_shift(struct dp_packet *b, int delta)
: true);
if (delta != 0) {
+#ifdef DPDK_NETDEV
+ if (b->source == DPBUF_DPDK) {
+ dp_packet_mbuf_shift(b, delta);
+ return;
+ }
+#endif
char *dst = (char *) dp_packet_data(b) + delta;
memmove(dst, dp_packet_data(b), dp_packet_size(b));
dp_packet_set_data(b, dst);
diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index 14e2551..6ca4e98 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -80,6 +80,11 @@ struct dp_packet {
};
};
+#ifdef DPDK_NETDEV
+#define MBUF_BUF_END(BUF_ADDR, BUF_LEN) \
+ (char *) (((char *) BUF_ADDR) + BUF_LEN)
+#endif
+
static inline void *dp_packet_data(const struct dp_packet *);
static inline void dp_packet_set_data(struct dp_packet *, void *);
static inline void *dp_packet_base(const struct dp_packet *);
@@ -133,6 +138,11 @@ static inline void *dp_packet_at(const struct dp_packet *,
size_t offset,
size_t size);
static inline void *dp_packet_at_assert(const struct dp_packet *,
size_t offset, size_t size);
+#ifdef DPDK_NETDEV
+void
+dp_packet_mbuf_write(struct rte_mbuf *mbuf, int16_t ofs, uint32_t len,
+ const void *data);
+#endif
static inline void *dp_packet_tail(const struct dp_packet *);
static inline void *dp_packet_end(const struct dp_packet *);
--
2.7.4
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