linux/drivers/base/dd.c, branch v5.8

driver core: Don't do deferred probe in parallel with kernel_init thread

2020-07-10T13:20:38Z

The current deferred probe implementation can mess up suspend/resume ordering if deferred probe thread is kicked off in parallel with the main initcall thread (kernel_init thread) [1]. For example: Say device-B is a consumer of device-A. Initcall thread Deferred probe thread =============== ===================== 1. device-A is added. 2. device-B is added. 3. dpm_list is now [device-A, device-B]. 4. driver-A defers probe of device-A. 5. device-A is moved to end of dpm_list 6. dpm_list is now [device-B, device-A] 7. driver-B is registereed and probes device-B. 8. dpm_list stays as [device-B, device-A]. The reverse order of dpm_list is used for suspend. So in this case device-A would incorrectly get suspended before device-B. Commit 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") kicked off the deferred probe thread early during boot to run in parallel with the initcall thread and caused suspend/resume regressions. This patch removes the parallel run of the deferred probe thread to avoid the suspend/resume regressions. [1] - https://lore.kernel.org/lkml/CAGETcx8W96KAw-d_siTX4qHB_-7ddk0miYRDQeHE6E0_8qx-6Q@mail.gmail.com/ Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") Signed-off-by: Saravana Kannan Tested-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20200701194259.3337652-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Remove check in driver_deferred_probe_force_trigger()

2020-05-19T14:48:23Z

The whole point behind adding driver_deferred_probe_force_trigger() in commit 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") was to skip the check for driver_deferred_probe_enable. Otherwise, it's identical to driver_deferred_probe_trigger(). Delete the check in driver_deferred_probe_force_trigger() so that fw_devlink_pause() and fw_devlink_resume() can kick off deferred probe as intended. Without doing this forced deferred probe trigger, some platforms seem to be crashing during boot because they assume probe order of devices. Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20200517173453.157703-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: fw_devlink: Add support for batching fwnode parsing

2020-05-15T14:34:52Z

The amount of time spent parsing fwnodes of devices can become really high if the devices are added in an non-ideal order. Worst case can be O(N^2) when N devices are added. But this can be optimized to O(N) by adding all the devices and then parsing all their fwnodes in one batch. This commit adds fw_devlink_pause() and fw_devlink_resume() to allow doing this. Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20200515053500.215929-4-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

Merge v5.7-rc5 into driver-core-next

2020-05-11T07:00:09Z

We want the driver core fixes in here and this resolves a merge issue with drivers/base/dd.c Signed-off-by: Greg Kroah-Hartman

driver core: Add missing '\n' in log messages

2020-04-28T19:05:42Z

Message logged by 'dev_xxx()' or 'pr_xxx()' should end with a '\n'. While at it, convert some "printk(KERN_" into equivalent but less verbose (pr|dev)_xxx functions. Signed-off-by: Christophe JAILLET Link: https://lore.kernel.org/r/20200411133158.27390-1-christophe.jaillet@wanadoo.fr Signed-off-by: Greg Kroah-Hartman

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