MFC r271946 and r272595:

Improve transmit sending offload, TSO, algorithm in general. This
change allows all HCAs from Mellanox Technologies to function properly
when TSO is enabled. See r271946 and r272595 for more details about
this commit.

Sponsored by:	Mellanox Technologies

1 files changed, 31 insertions, 0 deletions

diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
index b66ea60..0c67347 100644
--- a/sys/kern/uipc_sockbuf.c
+++ b/sys/kern/uipc_sockbuf.c
@@ -1015,6 +1015,37 @@ sbsndptr(struct sockbuf *sb, u_int off, u_int len, u_int *moff)
 }
 
 /*
+ * Return the first mbuf and the mbuf data offset for the provided
+ * send offset without changing the "sb_sndptroff" field.
+ */
+struct mbuf *
+sbsndmbuf(struct sockbuf *sb, u_int off, u_int *moff)
+{
+	struct mbuf *m;
+
+	KASSERT(sb->sb_mb != NULL, ("%s: sb_mb is NULL", __func__));
+
+	/*
+	 * If the "off" is below the stored offset, which happens on
+	 * retransmits, just use "sb_mb":
+	 */
+	if (sb->sb_sndptr == NULL || sb->sb_sndptroff > off) {
+		m = sb->sb_mb;
+	} else {
+		m = sb->sb_sndptr;
+		off -= sb->sb_sndptroff;
+	}
+	while (off > 0 && m != NULL) {
+		if (off < m->m_len)
+			break;
+		off -= m->m_len;
+		m = m->m_next;
+	}
+	*moff = off;
+	return (m);
+}
+
+/*
  * Drop a record off the front of a sockbuf and move the next record to the
  * front.
  */