Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 7 Apr 2020 09:50:44 +0200 | Subject | Re: [RFC][PATCH] driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires |
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Hi John,
On Tue, Apr 7, 2020 at 9:06 AM John Stultz <john.stultz@linaro.org> wrote: > In commit c8c43cee29f6 ("driver core: Fix > driver_deferred_probe_check_state() logic"), we set the default > driver_deferred_probe_timeout value to 30 seconds to allow for > drivers that are missing dependencies to have some time so that > the dependency may be loaded from userland after initcalls_done > is set. > > However, Yoshihiro Shimoda reported that on his device that > expects to have unmet dependencies (due to "optional links" in > its devicetree), was failing to mount the NFS root. > > In digging further, it seemed the problem was that while the > device properly probes after waiting 30 seconds for any missing > modules to load, the ip_auto_config() had already failed, > resulting in NFS to fail. This was due to ip_auto_config() > calling wait_for_device_probe() which doesn't wait for the > driver_deferred_probe_timeout to fire. > > This patch tries to fix the issue by creating a waitqueue > for the driver_deferred_probe_timeout, and calling wait_event() > to make sure driver_deferred_probe_timeout is zero in > wait_for_device_probe() to make sure all the probing is > finished. > > NOTE: I'm not 100% sure this won't have other unwanted side > effects (I don't have failing hardware myself to validate), > so I'd apprecate testing and close review. > > If this approach doesn't work, I'll simply set the default > driver_deferred_probe_timeout value back to zero, to avoid any > behavioral change from before. > > Thanks to Geert for chasing down that ip_auto_config was why NFS > was failing in this case! > > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> > Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> > Cc: Jakub Kicinski <kuba@kernel.org> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > Cc: Rob Herring <robh@kernel.org> > Cc: Geert Uytterhoeven <geert@linux-m68k.org> > Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> > Cc: netdev <netdev@vger.kernel.org> > Cc: linux-pm@vger.kernel.org > Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> > Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") > Signed-off-by: John Stultz <john.stultz@linaro.org>
Thanks, this fixes the issue for me!
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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
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