On 7/17/2020 2:57 PM, Vladimir Oltean wrote: > 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. > This approach doesn't seem bad to me. We then document that NETIF_F_PHY_HWTSTAMP should only set of the correct conditions are met. > Thanks, > -Vladimir >
