| Message ID | 20200408072650.1731-1-john.stultz@linaro.org (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | [RFC,v2,1/2] driver core: Revert default driver_deferred_probe_timeout value to 0 | expand |
Hi John, > From: John Stultz, Sent: Wednesday, April 8, 2020 4:27 PM > > In commit c8c43cee29f6 ("driver core: Fix > driver_deferred_probe_check_state() logic"), we both cleaned up > the logic and also 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. > > Fixing that issue is possible, but could also introduce 30 > second delays in bootups for users who don't have any > missing dependencies, which is not ideal. > > So I think the best solution to avoid any regressions is to > revert back to a default timeout value of zero, and allow > systems that need to utilize the timeout in order for userland > to load any modules that supply misisng dependencies in the dts > to specify the timeout length via the exiting documented boot > argument. > > 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> Thank you for the patch! This patch could fix the issue on my environment. So, Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Best regards, Yoshihiro Shimoda
On Wed, Apr 8, 2020 at 9:26 AM John Stultz <john.stultz@linaro.org> wrote: > In commit c8c43cee29f6 ("driver core: Fix > driver_deferred_probe_check_state() logic"), we both cleaned up > the logic and also 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. > > Fixing that issue is possible, but could also introduce 30 > second delays in bootups for users who don't have any > missing dependencies, which is not ideal. > > So I think the best solution to avoid any regressions is to > revert back to a default timeout value of zero, and allow > systems that need to utilize the timeout in order for userland > to load any modules that supply misisng dependencies in the dts > to specify the timeout length via the exiting documented boot > argument. > > 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> Works fine with all four combinations (CONFIG_IPMMU_VMSA=y/n and CONFIG_MODULES=y/n) on Renesas Salvator-X(S) with R-Car Gen3. Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Gr{oetje,eeting}s, Geert
diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 06ec0e851fa1..908ae4d7805e 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -224,16 +224,7 @@ static int deferred_devs_show(struct seq_file *s, void *data) } DEFINE_SHOW_ATTRIBUTE(deferred_devs); -#ifdef CONFIG_MODULES -/* - * In the case of modules, set the default probe timeout to - * 30 seconds to give userland some time to load needed modules - */ -int driver_deferred_probe_timeout = 30; -#else -/* In the case of !modules, no probe timeout needed */ -int driver_deferred_probe_timeout = -1; -#endif +int driver_deferred_probe_timeout; EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); static int __init deferred_probe_timeout_setup(char *str) @@ -266,7 +257,7 @@ int driver_deferred_probe_check_state(struct device *dev) return -ENODEV; } - if (!driver_deferred_probe_timeout) { + if (!driver_deferred_probe_timeout && initcalls_done) { dev_WARN(dev, "deferred probe timeout, ignoring dependency"); return -ETIMEDOUT; }
In commit c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic"), we both cleaned up the logic and also 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. Fixing that issue is possible, but could also introduce 30 second delays in bootups for users who don't have any missing dependencies, which is not ideal. So I think the best solution to avoid any regressions is to revert back to a default timeout value of zero, and allow systems that need to utilize the timeout in order for userland to load any modules that supply misisng dependencies in the dts to specify the timeout length via the exiting documented boot argument. 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> --- drivers/base/dd.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)