| Message ID | 1442844182-27787-21-git-send-email-tomeu.vizoso@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/21/2015 09:03 AM, Tomeu Vizoso wrote: > Add a field to struct device that instructs the device-driver core to > defer the probe of this device until the late_initcall level. This is true until the next patch with moves deferred probe processing to device_initcall_sync. So disabling this option alone won't totally revert to current behaviour. I guess patch 21 could be reverted if necessary. > > By letting all built-in drivers to register before starting to probe, we > can avoid any deferred probes by probing dependencies on demand. > > Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> > > --- > > Changes in v4: > - Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in > machines with initcalls that depend on devices probing at a given time. > > drivers/base/Kconfig | 18 ++++++++++++++++++ > drivers/base/dd.c | 7 +++++++ > include/linux/device.h | 2 ++ > 3 files changed, 27 insertions(+) > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index 98504ec99c7d..44b5d33b1f49 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -324,4 +324,22 @@ config CMA_ALIGNMENT > > endif > > +config DELAY_DEVICE_PROBES > + bool "Allow delaying the probe of some devices" I'd like to hide visibility of this behind EXPERT. > + default y > + help > + Devices can be matched to a driver and probed from the moment they > + are registered, but early during boot their probes are likely to be > + deferred because some dependency isn't available yet because most > + drivers haven't been registered yet. > + > + Enabling this option allows the device registration code to delay the > + probing of a specific device until device_initcall_sync, when all > + built-in drivers have been registered already. > + > + In some platforms there may be implicit assumptions about when some > + devices are probed, so enabling this option could cause problems there. > + > + If unsure, say Y here. > + > endmenu > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 7dc04ee81c8b..269ea76c1a4f 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -417,6 +417,13 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > if (!device_is_registered(dev)) > return -ENODEV; > > +#if IS_ENABLED(CONFIG_DELAY_DEVICE_PROBES) This can be moved to the if. > + if (!driver_deferred_probe_enable && dev->probe_late) { > + driver_deferred_probe_add(dev); > + return 0; > + } > +#endif > + > pr_debug("bus: '%s': %s: matched device %s with driver %s\n", > drv->bus->name, __func__, dev_name(dev), drv->name); > > diff --git a/include/linux/device.h b/include/linux/device.h > index 8e7b806f0744..e64f4c7e243d 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -744,6 +744,7 @@ struct device_dma_parameters { > * > * @offline_disabled: If set, the device is permanently online. > * @offline: Set after successful invocation of bus type's .offline(). > + * @probe_late: If set, device will be probed in the late initcall level. > * > * At the lowest level, every device in a Linux system is represented by an > * instance of struct device. The device structure contains the information > @@ -828,6 +829,7 @@ struct device { > > bool offline_disabled:1; > bool offline:1; > + bool probe_late:1; > }; > > static inline struct device *kobj_to_dev(struct kobject *kobj) >
On 26 September 2015 at 20:15, Rob Herring <robh@kernel.org> wrote: > On 09/21/2015 09:03 AM, Tomeu Vizoso wrote: >> Add a field to struct device that instructs the device-driver core to >> defer the probe of this device until the late_initcall level. > > This is true until the next patch with moves deferred probe processing > to device_initcall_sync. So disabling this option alone won't totally > revert to current behaviour. I guess patch 21 could be reverted if > necessary. Actually, the goal with that commit was to prevent potential problems due to the increased pressure on late_initcall, as suggested by Grygorii Strashko, but I haven't found yet any evidence of it being needed, and in my testing the series boot all boards in kernelci with or without this commit. So I would just not commit it for now and only consider applying it later if someone reports a problem. >> By letting all built-in drivers to register before starting to probe, we >> can avoid any deferred probes by probing dependencies on demand. >> >> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> >> >> --- >> >> Changes in v4: >> - Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in >> machines with initcalls that depend on devices probing at a given time. >> >> drivers/base/Kconfig | 18 ++++++++++++++++++ >> drivers/base/dd.c | 7 +++++++ >> include/linux/device.h | 2 ++ >> 3 files changed, 27 insertions(+) >> >> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig >> index 98504ec99c7d..44b5d33b1f49 100644 >> --- a/drivers/base/Kconfig >> +++ b/drivers/base/Kconfig >> @@ -324,4 +324,22 @@ config CMA_ALIGNMENT >> >> endif >> >> +config DELAY_DEVICE_PROBES >> + bool "Allow delaying the probe of some devices" > > I'd like to hide visibility of this behind EXPERT. Done. >> + default y >> + help >> + Devices can be matched to a driver and probed from the moment they >> + are registered, but early during boot their probes are likely to be >> + deferred because some dependency isn't available yet because most >> + drivers haven't been registered yet. >> + >> + Enabling this option allows the device registration code to delay the >> + probing of a specific device until device_initcall_sync, when all >> + built-in drivers have been registered already. >> + >> + In some platforms there may be implicit assumptions about when some >> + devices are probed, so enabling this option could cause problems there. >> + >> + If unsure, say Y here. >> + >> endmenu >> diff --git a/drivers/base/dd.c b/drivers/base/dd.c >> index 7dc04ee81c8b..269ea76c1a4f 100644 >> --- a/drivers/base/dd.c >> +++ b/drivers/base/dd.c >> @@ -417,6 +417,13 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) >> if (!device_is_registered(dev)) >> return -ENODEV; >> >> +#if IS_ENABLED(CONFIG_DELAY_DEVICE_PROBES) > > This can be moved to the if. Done. Thanks, Tomeu >> + if (!driver_deferred_probe_enable && dev->probe_late) { >> + driver_deferred_probe_add(dev); >> + return 0; >> + } >> +#endif >> + >> pr_debug("bus: '%s': %s: matched device %s with driver %s\n", >> drv->bus->name, __func__, dev_name(dev), drv->name); >> >> diff --git a/include/linux/device.h b/include/linux/device.h >> index 8e7b806f0744..e64f4c7e243d 100644 >> --- a/include/linux/device.h >> +++ b/include/linux/device.h >> @@ -744,6 +744,7 @@ struct device_dma_parameters { >> * >> * @offline_disabled: If set, the device is permanently online. >> * @offline: Set after successful invocation of bus type's .offline(). >> + * @probe_late: If set, device will be probed in the late initcall level. >> * >> * At the lowest level, every device in a Linux system is represented by an >> * instance of struct device. The device structure contains the information >> @@ -828,6 +829,7 @@ struct device { >> >> bool offline_disabled:1; >> bool offline:1; >> + bool probe_late:1; >> }; >> >> static inline struct device *kobj_to_dev(struct kobject *kobj) >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
On Tue, Sep 29, 2015 at 3:05 AM, Tomeu Vizoso <tomeu.vizoso@collabora.com> wrote: > On 26 September 2015 at 20:15, Rob Herring <robh@kernel.org> wrote: >> On 09/21/2015 09:03 AM, Tomeu Vizoso wrote: >>> Add a field to struct device that instructs the device-driver core to >>> defer the probe of this device until the late_initcall level. >> >> This is true until the next patch with moves deferred probe processing >> to device_initcall_sync. So disabling this option alone won't totally >> revert to current behaviour. I guess patch 21 could be reverted if >> necessary. > > Actually, the goal with that commit was to prevent potential problems > due to the increased pressure on late_initcall, as suggested by > Grygorii Strashko, but I haven't found yet any evidence of it being > needed, and in my testing the series boot all boards in kernelci with > or without this commit. So I would just not commit it for now and only > consider applying it later if someone reports a problem. I had similar concerns with assumptions about ordering WRT late_initcall. I would keep this for now. Rob
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 98504ec99c7d..44b5d33b1f49 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -324,4 +324,22 @@ config CMA_ALIGNMENT endif +config DELAY_DEVICE_PROBES + bool "Allow delaying the probe of some devices" + default y + help + Devices can be matched to a driver and probed from the moment they + are registered, but early during boot their probes are likely to be + deferred because some dependency isn't available yet because most + drivers haven't been registered yet. + + Enabling this option allows the device registration code to delay the + probing of a specific device until device_initcall_sync, when all + built-in drivers have been registered already. + + In some platforms there may be implicit assumptions about when some + devices are probed, so enabling this option could cause problems there. + + If unsure, say Y here. + endmenu diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 7dc04ee81c8b..269ea76c1a4f 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -417,6 +417,13 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) if (!device_is_registered(dev)) return -ENODEV; +#if IS_ENABLED(CONFIG_DELAY_DEVICE_PROBES) + if (!driver_deferred_probe_enable && dev->probe_late) { + driver_deferred_probe_add(dev); + return 0; + } +#endif + pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); diff --git a/include/linux/device.h b/include/linux/device.h index 8e7b806f0744..e64f4c7e243d 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -744,6 +744,7 @@ struct device_dma_parameters { * * @offline_disabled: If set, the device is permanently online. * @offline: Set after successful invocation of bus type's .offline(). + * @probe_late: If set, device will be probed in the late initcall level. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -828,6 +829,7 @@ struct device { bool offline_disabled:1; bool offline:1; + bool probe_late:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj)
Add a field to struct device that instructs the device-driver core to defer the probe of this device until the late_initcall level. By letting all built-in drivers to register before starting to probe, we can avoid any deferred probes by probing dependencies on demand. Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> --- Changes in v4: - Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in machines with initcalls that depend on devices probing at a given time. drivers/base/Kconfig | 18 ++++++++++++++++++ drivers/base/dd.c | 7 +++++++ include/linux/device.h | 2 ++ 3 files changed, 27 insertions(+)