From: Saravana Kannan saravanak@google.com
[ Upstream commit 5ee76c256e928455212ab759c51d198fedbe7523 ]
Mounting NFS rootfs was timing out when deferred_probe_timeout was non-zero [1]. This was because ip_auto_config() initcall times out waiting for the network interfaces to show up when deferred_probe_timeout was non-zero. While ip_auto_config() calls wait_for_device_probe() to make sure any currently running deferred probe work or asynchronous probe finishes, that wasn't sufficient to account for devices being deferred until deferred_probe_timeout.
Commit 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") tried to fix that by making sure wait_for_device_probe() waits for deferred_probe_timeout to expire before returning.
However, if wait_for_device_probe() is called from the kernel_init() context:
- Before deferred_probe_initcall() [2], it causes the boot process to hang due to a deadlock.
- After deferred_probe_initcall() [3], it blocks kernel_init() from continuing till deferred_probe_timeout expires and beats the point of deferred_probe_timeout that's trying to wait for userspace to load modules.
Neither of this is good. So revert the changes to wait_for_device_probe().
[1] - https://lore.kernel.org/lkml/TYAPR01MB45443DF63B9EF29054F7C41FD8C60@TYAPR01M... [2] - https://lore.kernel.org/lkml/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/ [3] - https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@linutronix.de/
Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") Cc: John Stultz jstultz@google.com 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: Rob Herring robh@kernel.org Cc: Geert Uytterhoeven geert@linux-m68k.org Cc: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com Cc: Robin Murphy robin.murphy@arm.com Cc: Andy Shevchenko andy.shevchenko@gmail.com Cc: Sudeep Holla sudeep.holla@arm.com Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Naresh Kamboju naresh.kamboju@linaro.org Cc: Basil Eljuse Basil.Eljuse@arm.com Cc: Ferry Toth fntoth@gmail.com Cc: Arnd Bergmann arnd@arndb.de Cc: Anders Roxell anders.roxell@linaro.org Cc: linux-pm@vger.kernel.org Reported-by: Nathan Chancellor nathan@kernel.org Reported-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Tested-by: Geert Uytterhoeven geert+renesas@glider.be Acked-by: John Stultz jstultz@google.com Signed-off-by: Saravana Kannan saravanak@google.com Link: https://lore.kernel.org/r/20220526034609.480766-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Reviewed-by: Rafael J. Wysocki rafael@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/dd.c | 5 ----- 1 file changed, 5 deletions(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 4f4e8aedbd2c..f9d9f1ad9215 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -250,7 +250,6 @@ 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) { @@ -302,7 +301,6 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe) dev_info(p->device, "deferred probe pending\n"); mutex_unlock(&deferred_probe_mutex); - wake_up_all(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
@@ -706,9 +704,6 @@ 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);