git: 2eb9b105f3e4 - stable/12 - cxgb(4): Rework my commit 9dc7c250.

[Alexander Motin]

The branch stable/12 has been updated by mav:

URL: https://cgit.FreeBSD.org/src/commit/?id=2eb9b105f3e473e1438944cc95e36d7912b3296e

commit 2eb9b105f3e473e1438944cc95e36d7912b3296e
Author:     Alexander Motin <mav at FreeBSD.org>
AuthorDate: 2021-02-22 22:21:05 +0000
Commit:     Alexander Motin <mav at FreeBSD.org>
CommitDate: 2021-02-25 01:40:56 +0000

    cxgb(4): Rework my commit 9dc7c250.
    
    The previous implementation was reported to try to coalesce packets
    in situations when it should not, that resulted in assertion later.
    This implementation better checks the first packet of the chain for
    the coallescing elligibility.
    
    (cherry picked from commit d510bf133d045d6c83742aeda6949bec150f6cbf)
---
 sys/dev/cxgb/cxgb_sge.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/sys/dev/cxgb/cxgb_sge.c b/sys/dev/cxgb/cxgb_sge.c
index 489d74459ae1..07eb91a4d04c 100644
--- a/sys/dev/cxgb/cxgb_sge.c
+++ b/sys/dev/cxgb/cxgb_sge.c
@@ -312,20 +312,22 @@ set_wr_hdr(struct work_request_hdr *wrp, uint32_t wr_hi, uint32_t wr_lo)
 struct coalesce_info {
 	int count;
 	int nbytes;
+	int noncoal;
 };
 
 static int
 coalesce_check(struct mbuf *m, void *arg)
 {
 	struct coalesce_info *ci = arg;
-	int *count = &ci->count;
-	int *nbytes = &ci->nbytes;
-
-	if ((*nbytes == 0) || ((*nbytes + m->m_len <= 10500) &&
-	    (*count < 7) && (m->m_next == NULL) &&
-	    ((mtod(m, vm_offset_t) & PAGE_MASK) + m->m_len <= PAGE_SIZE))) {
-		*count += 1;
-		*nbytes += m->m_len;
+
+	if ((m->m_next != NULL) ||
+	    ((mtod(m, vm_offset_t) & PAGE_MASK) + m->m_len > PAGE_SIZE))
+		ci->noncoal = 1;
+
+	if ((ci->count == 0) || (ci->noncoal == 0 && (ci->count < 7) &&
+	    (ci->nbytes + m->m_len <= 10500))) {
+		ci->count++;
+		ci->nbytes += m->m_len;
 		return (1);
 	}
 	return (0);
@@ -342,7 +344,7 @@ cxgb_dequeue(struct sge_qset *qs)
 		return TXQ_RING_DEQUEUE(qs);
 
 	m_head = m_tail = NULL;
-	ci.count = ci.nbytes = 0;
+	ci.count = ci.nbytes = ci.noncoal = 0;
 	do {
 		m = TXQ_RING_DEQUEUE_COND(qs, coalesce_check, &ci);
 		if (m_head == NULL) {