driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction

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@TYAPR01MB4544.jpnprd01.prod.outlook.com/
[2] - https://lore.kernel.org/lkml/[email protected]/
[3] - https://lore.kernel.org/lkml/[email protected]/

Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires")
Cc: John Stultz <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Alexey Kuznetsov <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Yoshihiro Shimoda <[email protected]>
Cc: Robin Murphy <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Sudeep Holla <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Naresh Kamboju <[email protected]>
Cc: Basil Eljuse <[email protected]>
Cc: Ferry Toth <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Anders Roxell <[email protected]>
Cc: [email protected]
Reported-by: Nathan Chancellor <[email protected]>
Reported-by: Sebastian Andrzej Siewior <[email protected]>
Tested-by: Geert Uytterhoeven <[email protected]>
Acked-by: John Stultz <[email protected]>
Signed-off-by: Saravana Kannan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions