From ce68929f07de0780c1afbbeef9aa6cf3550163d6 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 22 Apr 2020 20:32:43 +0000 Subject: driver core: Revert default driver_deferred_probe_timeout value to 0 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 --- drivers/base/dd.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) (limited to 'drivers/base/dd.c') 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; } -- cgit v1.2.1 From 4ccc03e28ec309173f434fa38b48b6ad65ff5d1b Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 22 Apr 2020 20:32:44 +0000 Subject: driver core: Use dev_warn() instead of dev_WARN() for deferred_probe_timeout warnings 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 --- drivers/base/dd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/base/dd.c') diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 908ae4d7805e..9c88afa5c74a 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -258,7 +258,7 @@ int driver_deferred_probe_check_state(struct device *dev) } if (!driver_deferred_probe_timeout && initcalls_done) { - dev_WARN(dev, "deferred probe timeout, ignoring dependency"); + dev_warn(dev, "deferred probe timeout, ignoring dependency"); return -ETIMEDOUT; } -- cgit v1.2.1 From 35a672363ab3e8dfe4ebcadb4dd0b2d06bb85ebe Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 22 Apr 2020 20:32:45 +0000 Subject: driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires 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 --- drivers/base/dd.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/base/dd.c') diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9c88afa5c74a..94037be7f5d7 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -226,6 +226,7 @@ DEFINE_SHOW_ATTRIBUTE(deferred_devs); int driver_deferred_probe_timeout; EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); +static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue); static int __init deferred_probe_timeout_setup(char *str) { @@ -275,6 +276,7 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) dev_info(private->device, "deferred probe pending"); + wake_up(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -649,6 +651,9 @@ int driver_probe_done(void) */ void wait_for_device_probe(void) { + /* wait for probe timeout */ + wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout); + /* wait for the deferred probe workqueue to finish */ flush_work(&deferred_probe_work); -- cgit v1.2.1