On Thu, 22 Oct 2020 19:25:40 -0700 Xie He wrote: > On Thu, Oct 22, 2020 at 6:56 PM Xie He <xie.he.0...@gmail.com> wrote: > > My patch isn't complete. Because there are so many drivers with this > > problem, I feel it's hard to solve them all at once. So I only grepped > > "skb_padto" under "drivers/net/ethernet". There are other drivers > > under "ethernet" using "skb_pad", "skb_put_padto" or "eth_skb_pad". > > There are also (fake) Ethernet drivers under "drivers/net/wireless". I > > feel it'd take a long time and also be error-prone to solve them all, > > so I feel it'd be the best if there are other solutions. > > BTW, I also see some Ethernet drivers calling skb_push to prepend > strange headers to the skbs. For example, > > drivers/net/ethernet/mellanox/mlxsw/switchx2.c prepends a header of > MLXSW_TXHDR_LEN (16). > > We can't send shared skbs to these drivers either because they modify the > skbs. > > It seems to me that many drivers have always assumed that they can > modify the skb whenever needed. They've never considered there might > be shared skbs. I guess adding IFF_TX_SKB_SHARING to ether_setup was a > bad idea. It not only made the code less clean, but also didn't agree > with the actual situations of the drivers.
Indeed. If we remove IFF_TX_SKB_SHARING from ether_setup we may need to add the flag to the drivers that used to work, otherwise people using pktgen will see a regression.
