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[34.48.4.250]) by smtp.gmail.com with ESMTPSA id 00721157ae682-823f74c7590sm62472597b3.46.2026.08.10.12.55.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Aug 2026 12:55:58 -0700 (PDT) Date: Mon, 10 Aug 2026 15:55:58 -0400 From: Willem de Bruijn To: Rongguang Wei , Willem de Bruijn , kuba@kernel.org, jasowangio@gmail.com, andrew+netdev@lunn.ch Cc: netdev@vger.kernel.org, Rongguang Wei , Willem de Bruijn Message-ID: In-Reply-To: <09030f3e-811c-48a8-ad9c-6bf9432e73e4@163.com> References: <20260807070914.112698-1-clementwei90@163.com> <09030f3e-811c-48a8-ad9c-6bf9432e73e4@163.com> Subject: Re: [PATCH net v2] tap: fix incorrect variable used for USO check in set_offload() Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Rongguang Wei wrote: > Willem de Bruijn wrote: > > Rongguang Wei wrote: > >> From: Rongguang Wei > >> > >> The USO features in set_offload() incorrectly uses feature_mask and > >> features argument. > >> > >> The USO feature was written to the local features variable instead of > >> feature_mask. All other offload bits (TSO, TSO_ECN) are stored in > >> feature_mask which becomes tap->tap_features and is used by > >> tap_handle_frame() for GSO segmentation. Without NETIF_F_GSO_UDP_L4 > >> in tap->tap_features, making USO on tap effectively non-functional. > >> > >> Keeping the USO handling inside the TUN_F_CSUM block avoids enabling > >> GRO/LRO when userspace requests USO without CSUM. > >> > >> Fixes: 399e0827642f ("driver/net/tun: Added features for USO.") > >> Signed-off-by: Rongguang Wei > >> Reviewed-by: Willem de Bruijn > > > > Reviewed-by: Willem de Bruijn > > > > Substantially changed patch, please don't keep Reviewed-by tags across > > non-trivial changes. That said, I do agree, so adding it again. > > > >> --- > >> v2: Fix more incorrect variable in USO check. > >> https://lore.kernel.org/netdev/20260806163949.2807698-1-kuba@kernel.org/ > >> v1: https://lore.kernel.org/netdev/20260805072121.117472-1-clementwei90@163.com/ > >> --- > >> drivers/net/tap.c | 5 ++--- > >> 1 file changed, 2 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/net/tap.c b/drivers/net/tap.c > >> index 5d2d34d24ce8..d4ca2fee538b 100644 > >> --- a/drivers/net/tap.c > >> +++ b/drivers/net/tap.c > >> @@ -883,7 +883,7 @@ static int set_offload(struct tap_queue *q, unsigned long arg) > >> > >> /* TODO: for now USO4 and USO6 should work simultaneously */ > >> if ((arg & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6)) > >> - features |= NETIF_F_GSO_UDP_L4; > >> + feature_mask |= NETIF_F_GSO_UDP_L4; > > > > Drivers/net/tun seems to have this same issue. > > > > Do you want to take a look or shall I? > > > Hi, > I have check the code in drivers/net/tun.c. > In tun.c, the tun's all offload bits go into features argument and > I think tun.c does not have this issue. Oh indeed. Thanks for checking. To repeat, this patch LGTM.