git: bbd30927b1af - main - bge: disable TXCSUM if UDP transmit checksum offloading is disabled

The branch main has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=bbd30927b1af44226c8de0512912a7fedfce2824

commit bbd30927b1af44226c8de0512912a7fedfce2824
Author:     Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2026-01-16 12:32:13 +0000
Commit:     Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2026-01-16 12:36:53 +0000

    bge: disable TXCSUM if UDP transmit checksum offloading is disabled
    
    The bge interface is special with respect to transmit checksumi
    offloading. In the default settings, an bge interface announces TXCSUM
    capabilities, but only supports TCP/IPv4 and not UDP/IPv4 due to
    limitations of some of the NICs. This results in problems when the bge
    interface becomes a member of a bridge. Since currently only the
    TXCSUM capabilities are synced when a member is added to a bridge and
    not the protocol specific capabilities, this can result in a situation
    where UDP packets are sent out using a bge interface without having a
    correct checksum.
    To mitigate this problem, initially don't announce TXCSUM capabilities,
    when UDP transmit checksum is disabled. It is still possible to enable
    TXCSUM capabilities via ifconfig.
    
    PR:                     291420
    Reviewed by:            Timo Voelker
    MFC after:              3 days
    Differential Revision:  https://reviews.freebsd.org/D54486
---
 share/man/man4/bge.4 | 10 +++++++++-
 sys/dev/bge/if_bge.c | 14 +++++++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/share/man/man4/bge.4 b/share/man/man4/bge.4
index de559c16df3c..fdf46fec0073 100644
--- a/share/man/man4/bge.4
+++ b/share/man/man4/bge.4
@@ -29,7 +29,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 .\" THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd August 18, 2017
+.Dd January 16, 2026
 .Dt BGE 4
 .Os
 .Sh NAME
@@ -276,3 +276,11 @@ Also, due to the lack of hotplug support, Thunderbolt-based interfaces must not
 while the system is up as the kernel is currently unable to cope with a
 .Nm
 interface disappearing.
+.Pp
+The UDP transmit checksum offloading is disabled by default, see
+.Va dev.bge.%d.forced_udpcsum .
+To avoid problems when the interface is a member of a
+.Xr bridge 4
+interface, all transmit checksum offloading is initially disabled in this case.
+Transmit checksum offloading can be enabled using
+.Xr ifconfig 8 .
diff --git a/sys/dev/bge/if_bge.c b/sys/dev/bge/if_bge.c
index cf3084f9b768..2feb19bff677 100644
--- a/sys/dev/bge/if_bge.c
+++ b/sys/dev/bge/if_bge.c
@@ -3721,7 +3721,12 @@ bge_attach(device_t dev)
 	if_setgetcounterfn(ifp, bge_get_counter);
 	if_setsendqlen(ifp, BGE_TX_RING_CNT - 1);
 	if_setsendqready(ifp);
-	if_sethwassist(ifp, sc->bge_csum_features);
+	/* Initially enable checksum offloading either for all of IPv4, TCP/IPv4
+	 * and UDP/IPv4, or for none. This avoids problems when the interface
+	 * is added to a bridge.
+	 */
+	if (sc->bge_csum_features & CSUM_UDP)
+		if_sethwassist(ifp, sc->bge_csum_features);
 	if_setcapabilities(ifp, IFCAP_HWCSUM | IFCAP_VLAN_HWTAGGING |
 	    IFCAP_VLAN_MTU);
 	if ((sc->bge_flags & (BGE_FLAG_TSO | BGE_FLAG_TSO3)) != 0) {
@@ -3732,6 +3737,13 @@ bge_attach(device_t dev)
 	if_setcapabilitiesbit(ifp, IFCAP_VLAN_HWCSUM, 0);
 #endif
 	if_setcapenable(ifp, if_getcapabilities(ifp));
+	/*
+	 * Disable TXCSUM capability initially, if UDP checksum offloading is
+	 * not enabled. This avoids problems when the interface is added to a
+	 * bridge.
+	 */
+	if ((sc->bge_csum_features & CSUM_UDP) == 0)
+		if_setcapenablebit(ifp, 0, IFCAP_TXCSUM);
 #ifdef DEVICE_POLLING
 	if_setcapabilitiesbit(ifp, IFCAP_POLLING, 0);
 #endif