git: bedfac1f026f - main - nvmf_tcp: Fully honor kern.nvmf.tcp.max_transmit_data for C2H_DATA PDUs

The branch main has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=bedfac1f026fa8e2e6572ca380d89d74a01d5def

commit bedfac1f026fa8e2e6572ca380d89d74a01d5def
Author:     John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2024-09-05 21:14:36 +0000
Commit:     John Baldwin <jhb@FreeBSD.org>
CommitDate: 2024-09-05 21:14:36 +0000

    nvmf_tcp: Fully honor kern.nvmf.tcp.max_transmit_data for C2H_DATA PDUs
    
    The previous version of tcp_send_controller_data avoided sending a
    chain of multiple mbufs that exceeded the limit, but if an individual
    mbuf was larger than the limit it was sent as a single, over-sized
    PDU.  Fix by using m_split() to split individual mbufs larger than the
    limit.
    
    Note that this is not a protocol error, per se, as there is no limit
    on C2H_DATA PDU lengths (unlike the MAXH2CDATA parameter).  This fix
    just honors the administrative limit more faithfully.  This case is
    also very unlikely with the default limit of 256k.
    
    Sponsored by:   Chelsio Communications
---
 sys/dev/nvmf/nvmf_tcp.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/sys/dev/nvmf/nvmf_tcp.c b/sys/dev/nvmf/nvmf_tcp.c
index 67d239b63faf..22275aaa835b 100644
--- a/sys/dev/nvmf/nvmf_tcp.c
+++ b/sys/dev/nvmf/nvmf_tcp.c
@@ -1784,7 +1784,6 @@ tcp_send_controller_data(struct nvmf_capsule *nc, uint32_t data_offset,
 {
 	struct nvmf_tcp_qpair *qp = TQP(nc->nc_qpair);
 	struct nvme_sgl_descriptor *sgl;
-	struct mbuf *n, *p;
 	uint32_t data_len;
 	bool last_pdu, last_xfer;
 
@@ -1813,21 +1812,29 @@ tcp_send_controller_data(struct nvmf_capsule *nc, uint32_t data_offset,
 
 	/* Queue one more C2H_DATA PDUs containing the data from 'm'. */
 	while (m != NULL) {
+		struct mbuf *n;
 		uint32_t todo;
 
-		todo = m->m_len;
-		p = m;
-		n = p->m_next;
-		while (n != NULL) {
-			if (todo + n->m_len > qp->max_tx_data) {
-				p->m_next = NULL;
-				break;
-			}
-			todo += n->m_len;
-			p = n;
+		if (m->m_len > qp->max_tx_data) {
+			n = m_split(m, qp->max_tx_data, M_WAITOK);
+			todo = m->m_len;
+		} else {
+			struct mbuf *p;
+
+			todo = m->m_len;
+			p = m;
 			n = p->m_next;
+			while (n != NULL) {
+				if (todo + n->m_len > qp->max_tx_data) {
+					p->m_next = NULL;
+					break;
+				}
+				todo += n->m_len;
+				p = n;
+				n = p->m_next;
+			}
+			MPASS(m_length(m, NULL) == todo);
 		}
-		MPASS(m_length(m, NULL) == todo);
 
 		last_pdu = (n == NULL && last_xfer);
 		tcp_send_c2h_pdu(qp, nc->nc_sqe.cid, data_offset, m, todo,