git: 57e7572fcbe8 - stable/15 - iflib: handle transient errors from isc_txd_encap()

The branch stable/15 has been updated by kbowling:

URL: https://cgit.FreeBSD.org/src/commit/?id=57e7572fcbe84d45de5eddfba4b9c387c47c325f

commit 57e7572fcbe84d45de5eddfba4b9c387c47c325f
Author:     Andrew Gallatin <gallatin@FreeBSD.org>
AuthorDate: 2026-06-15 14:20:41 +0000
Commit:     Kevin Bowling <kbowling@FreeBSD.org>
CommitDate: 2026-10-29 05:28:16 +0000

    iflib: handle transient errors from isc_txd_encap()
    
    Until we introduced support for nic ktls offload, all error returns
    from isc_txd_encap() indicated a permanent failure. Iflib remapped all
    those failures to ENOMEM, which was treated by the tcp stack as a
    permanent error and passed back to the caller. This was done to avoid
    creating "infinite loops" where a packet couldn't be mapped for
    transmit, and kept being sent over and over.
    
    Now that we have support for nic ktls offload, some ktls offload
    drivers may return ENOBUFS from their encap function to indicate that,
    for example, the ktls context may not yet be fully initialized.  This
    needs to be treated as a transient error so that the TCP stack may
    re-try at a later time. To achieve this, pass the raw error back to
    the caller when the encap routine returns an error aside from EFBIG.
    
    Note that I audited all in-tree iflib drivers. Only ice and ixl ran
    return anything other than 0 from their encap, which is EFBIG. both of
    which are still treated as they were before.
    
    Testing with an out-of-tree ktls offload nic using iflib showed ENOMEM
    errors from sendmsg() before this change, and no more errors passed
    back to userspace after this change.
    
    Reviewed by: kp, sumit.saxena_broadcom.com
    Sponsored by: Netflix
    Differential Revision: https://reviews.freebsd.org/D57550
    
    (cherry picked from commit 074ff8746388b3ed8581a84a7eea7b4b3e1bfe23)
---
 sys/net/iflib.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/net/iflib.c b/sys/net/iflib.c
index 3f7b1b84b514..f8403ff7c1a4 100644
--- a/sys/net/iflib.c
+++ b/sys/net/iflib.c
@@ -3824,8 +3824,9 @@ defrag:
 				remap = 1;
 				goto defrag;
 			}
+			goto defrag_failed;
 		}
-		goto defrag_failed;
+		goto out_with_error;
 	}
 	/*
 	 * err can't possibly be non-zero here, so we don't neet to test it
@@ -3834,13 +3835,15 @@ defrag:
 	return (err);
 
 defrag_failed:
+	err = ENOMEM;
 	txq->ift_mbuf_defrag_failed++;
+out_with_error:
 	txq->ift_map_failed++;
 	m_freem(*m_headp);
 	DBG_COUNTER_INC(tx_frees);
 	*m_headp = NULL;
 	DBG_COUNTER_INC(encap_txd_encap_fail);
-	return (ENOMEM);
+	return (err);
 }
 
 static void