linux/drivers/base/dd.c, branch v5.7

driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires

2020-04-28T15:57:13Z

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. The downside to this solution is that kernel functionality that uses wait_for_device_probe(), will block until the driver_deferred_probe_timeout fires, regardless of if there is any missing dependencies. However, the previous patch reverts the default timeout value to zero, so this side-effect will only affect users who specify a driver_deferred_probe_timeout= value as a boot argument, where the additional delay would be beneficial to allow modules to load later during boot. Thanks to Geert for chasing down that ip_auto_config was why NFS was failing in this case! Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Rafael J. Wysocki Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: Robin Murphy Cc: Andy Shevchenko Cc: Sudeep Holla Cc: Andy Shevchenko Cc: Naresh Kamboju Cc: Basil Eljuse Cc: Ferry Toth Cc: Arnd Bergmann Cc: Anders Roxell Cc: linux-pm@vger.kernel.org Reported-by: Yoshihiro Shimoda Tested-by: Geert Uytterhoeven Tested-by: Yoshihiro Shimoda Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200422203245.83244-4-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Use dev_warn() instead of dev_WARN() for deferred_probe_timeout warnings

2020-04-28T15:57:13Z

In commit c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") and following changes the logic was changes slightly so that if there is no driver to match whats found in the dtb, we wait the sepcified seconds for modules to be loaded by userland, and then timeout, where as previously we'd print "ignoring dependency for device, assuming no driver" and immediately return -ENODEV after initcall_done. However, in the timeout case (which previously existed but was practicaly un-used without a boot argument), the timeout message uses dev_WARN(). This means folks are now seeing a big backtrace in their boot logs if there a entry in their dts that doesn't have a driver. To fix this, lets use dev_warn(), instead of dev_WARN() to match the previous error path. Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Rafael J. Wysocki Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: Robin Murphy Cc: Andy Shevchenko Cc: Sudeep Holla Cc: Andy Shevchenko Cc: Naresh Kamboju Cc: Basil Eljuse Cc: Ferry Toth Cc: Arnd Bergmann Cc: Anders Roxell Cc: linux-pm@vger.kernel.org Reviewed-by: Yoshihiro Shimoda Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200422203245.83244-3-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Revert default driver_deferred_probe_timeout value to 0

2020-04-28T15:56:26Z

This patch addresses a regression in 5.7-rc1+ 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" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Rafael J. Wysocki Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: Robin Murphy Cc: Andy Shevchenko Cc: Sudeep Holla Cc: Andy Shevchenko Cc: Naresh Kamboju Cc: Basil Eljuse Cc: Ferry Toth Cc: Arnd Bergmann Cc: Anders Roxell Reported-by: Yoshihiro Shimoda Tested-by: Yoshihiro Shimoda Tested-by: Geert Uytterhoeven Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200422203245.83244-2-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Replace open-coded list_last_entry()

2020-03-24T12:33:26Z

There is a place in the code where open-coded version of list entry accessors list_last_entry() is used. Replace that with the standard macro. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200324122023.9649-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

driver core: Read atomic counter once in driver_probe_done()

2020-03-24T12:33:25Z

Between printing the debug message and actual check atomic counter can be altered. For better debugging experience read atomic counter value only once. Signed-off-by: Andy Shevchenko Tested-by: Ferry Toth Link: https://lore.kernel.org/r/20200324122023.9649-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

driver core: Rename deferred_probe_timeout and make it global

2020-03-04T17:11:44Z

Since other subsystems (like regulator) have similar arbitrary timeouts for how long they try to resolve driver dependencies, rename deferred_probe_timeout to driver_deferred_probe_timeout and set it as global, so it can be shared. Cc: linux-pm@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Linus Walleij Cc: Thierry Reding Cc: Mark Brown Cc: Liam Girdwood Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Todd Kjos Cc: Len Brown Cc: Pavel Machek Cc: Ulf Hansson Cc: Kevin Hilman Cc: "Rafael J. Wysocki" Cc: Rob Herring Reviewed-by: Bjorn Andersson Reviewed-by: Rafael J. Wysocki Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200225050828.56458-6-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Remove driver_deferred_probe_check_state_continue()

2020-03-04T17:11:44Z

Now that driver_deferred_probe_check_state() works better, and we've converted the only user of driver_deferred_probe_check_state_continue() we can simply remove it and simplify some of the logic. Cc: linux-pm@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Linus Walleij Cc: Thierry Reding Cc: Mark Brown Cc: Liam Girdwood Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Todd Kjos Cc: Len Brown Cc: Pavel Machek Cc: Ulf Hansson Cc: Kevin Hilman Cc: "Rafael J. Wysocki" Cc: Rob Herring Reviewed-by: Bjorn Andersson Reviewed-by: Rafael J. Wysocki Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200225050828.56458-5-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Set deferred_probe_timeout to a longer default if CONFIG_MODULES is set

2020-03-04T17:11:44Z

When using modules, its common for the modules not to be loaded until quite late by userland. With the current code, driver_deferred_probe_check_state() will stop returning EPROBE_DEFER after late_initcall, which can cause module dependency resolution to fail after that. So allow a longer window of 30 seconds (picked somewhat arbitrarily, but influenced by the similar regulator core timeout value) in the case where modules are enabled. Cc: linux-pm@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Linus Walleij Cc: Thierry Reding Cc: Mark Brown Cc: Liam Girdwood Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Todd Kjos Cc: Len Brown Cc: Pavel Machek Cc: Ulf Hansson Cc: Kevin Hilman Cc: "Rafael J. Wysocki" Cc: Rob Herring Reviewed-by: Bjorn Andersson Reviewed-by: Rafael J. Wysocki Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200225050828.56458-3-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Fix driver_deferred_probe_check_state() logic

2020-03-04T17:11:44Z

driver_deferred_probe_check_state() has some uninituitive behavior. * From boot to late_initcall, it returns -EPROBE_DEFER * From late_initcall to the deferred_probe_timeout (if set) it returns -ENODEV * If the deferred_probe_timeout it set, after it fires, it returns -ETIMEDOUT This is a bit confusing, as its useful to have the function return -EPROBE_DEFER while the timeout is still running. This behavior has resulted in the somwhat duplicative driver_deferred_probe_check_state_continue() function being added. Thus this patch tries to improve the logic, so that it behaves as such: * If late_initcall has passed, and modules are not enabled it returns -ENODEV * If modules are enabled and deferred_probe_timeout is set, it returns -EPROBE_DEFER until the timeout, afterwhich it returns -ETIMEDOUT. * In all other cases, it returns -EPROBE_DEFER This will make the deferred_probe_timeout value much more functional, and will allow us to consolidate the driver_deferred_probe_check_state() and driver_deferred_probe_check_state_continue() logic in a later patch. Cc: linux-pm@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Linus Walleij Cc: Thierry Reding Cc: Mark Brown Cc: Liam Girdwood Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Todd Kjos Cc: Len Brown Cc: Pavel Machek Cc: Ulf Hansson Cc: Kevin Hilman Cc: "Rafael J. Wysocki" Cc: Rob Herring Signed-off-by: John Stultz Link: https://lore.kernel.org/r/20200225050828.56458-2-john.stultz@linaro.org Signed-off-by: Greg Kroah-Hartman

driver core: Print device when resources present in really_probe()

2020-01-14T15:14:48Z

If a device already has devres items attached before probing, a warning backtrace is printed. However, this backtrace does not reveal the offending device, leaving the user uninformed. Furthermore, using WARN_ON() causes systems with panic-on-warn to reboot. Fix this by replacing the WARN_ON() by a dev_crit() message. Abort probing the device, to prevent doing more damage to the device's resources. Signed-off-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20191206132219.28908-1-geert+renesas@glider.be Signed-off-by: Greg Kroah-Hartman