On Sat, Jul 18, 2020 at 12:13:42AM +0300, Sergey Organov wrote: > Vladimir Oltean <olteanv@xxxxxxxxx> writes: > > > I've tried to collect and summarize the conclusions of these discussions: > > https://patchwork.ozlabs.org/project/netdev/patch/20200711120842.2631-1-sorganov@xxxxxxxxx/ > > https://patchwork.ozlabs.org/project/netdev/patch/20200710113611.3398-5-kurt@xxxxxxxxxxxxx/ > > which were a bit surprising to me. Make sure they are present in the > > documentation. > > As one of participants of these discussions, I'm afraid I incline to > alternative approach to solving the issues current design has than the one > you advocate in these patch series. > > I believe its upper-level that should enforce common policies like > handling hw time stamping at outermost capable device, not random MAC > driver out there. > > I'd argue that it's then upper-level that should check PHY features, and > then do not bother MAC with ioctl() requests that MAC should not handle > in given configuration. This way, the checks for phy_has_hwtstamp() > won't be spread over multiple MAC drivers and will happily sit in the > upper-level ioctl() handler. > > In other words, I mean that it's approach taken in ethtool that I tend > to consider being the right one. > > Thanks, > -- Sergey Concretely speaking, what are you going to do for skb_defer_tx_timestamp() and skb_defer_rx_timestamp()? Not to mention subtle bugs like SKBTX_IN_PROGRESS. If you don't address those, it's pointless to move the phy_has_hwtstamp() check to net/core/dev_ioctl.c. The only way I see to fix the bug is to introduce a new netdev flag, NETIF_F_PHY_HWTSTAMP or something like that. Then I'd grep for all occurrences of phy_has_hwtstamp() in the kernel (which currently amount to a whopping 2 users, 3 with your FEC "fix"), and declare this netdevice flag in their list of features. Then, phy_has_hwtstamp() and phy_has_tsinfo() and what not can be moved to generic places (or at least, I think they can), and those places could proceed to advertise and enable PHY timestamping only if the MAC declared itself ready. But, it is a bit strange to introduce a netdev flag just to fix a bug, I think. Thanks, -Vladimir
