Hi David, On Sat, Sep 12, 2020 at 2:44 AM David Miller <da...@davemloft.net> wrote: > From: Geert Uytterhoeven <ge...@linux-m68k.org> > Date: Fri, 11 Sep 2020 08:32:55 +0200 > > > On Thu, Sep 10, 2020 at 9:20 PM David Miller <da...@davemloft.net> wrote: > >> From: Geert Uytterhoeven <geert+rene...@glider.be> > >> Date: Tue, 1 Sep 2020 17:02:37 +0200 > >> > >> > This reverts commit 124eee3f6955f7aa19b9e6ff5c9b6d37cb3d1e2c. > >> > > >> > Inami-san reported that this commit breaks bridge support in a Xen > >> > environment, and that reverting it fixes this. > >> > > >> > During system resume, bridge ports are no longer enabled, as that relies > >> > on the receipt of the NETDEV_CHANGE notification. This notification is > >> > not sent, as netdev_state_change() is no longer called. > >> > > >> > Note that the condition this commit intended to fix never existed > >> > upstream, as the patch triggering it and referenced in the commit was > >> > never applied upstream. Hence I can confirm s2ram on r8a73a4/ape6evm > >> > and sh73a0/kzm9g works fine before/after this revert. > >> > > >> > Reported-by Gaku Inami <gaku.inami...@renesas.com> > >> > Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be> > >> > >> Maybe you cannot reproduce it, but the problem is there and it still > >> looks very real to me. > >> > >> netdev_state_change() does two things: > >> > >> 1) Emit the NETDEV_CHANGE notification > >> > >> 2) Emit an rtmsg_ifinfo() netlink message, which in turn tries to access > >> the device statistics via ->ndo_get_stats*(). > >> > >> It is absolutely wrong to do #2 when netif_device_present() is false. > >> > >> So I cannot apply this patch as-is, sorry. > > > > Thanks a lot for looking into this! > > > > But doing #1 is still safe? That is the part that calls into the bridge > > code. So would moving the netif_device_present() check from > > linkwatch_do_dev() to netdev_state_change(), to prevent doing #2, be > > acceptable? > > I have a better question. Why is a software device like the bridge, > that wants to effectively exist and still receive netdev event > notifications, marking itself as not present? > > That's seems like the real bug here.
"dev" is not the bridge device, but the physical Ethernet interface, which may already be suspended during s2ram. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds