[5.18,146/339] driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction

Commit Message

Greg KH June 13, 2022, 10:09 a.m. UTC

From: Saravana Kannan <[e-mail]>

[ 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/[e-mail]/
[2] - https://lore.kernel.org/lkml/[e-mail]-3990X/
[3] - https://lore.kernel.org/lkml/[e-mail]/

Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires")
Cc: John Stultz <[e-mail]>
Cc: "David S. Miller" <[e-mail]>
Cc: Alexey Kuznetsov <[e-mail]>
Cc: Hideaki YOSHIFUJI <[e-mail]>
Cc: Jakub Kicinski <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Yoshihiro Shimoda <[e-mail]>
Cc: Robin Murphy <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: Sudeep Holla <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: Naresh Kamboju <[e-mail]>
Cc: Basil Eljuse <[e-mail]>
Cc: Ferry Toth <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Anders Roxell <[e-mail]>
Cc: [e-mail]
Reported-by: Nathan Chancellor <[e-mail]>
Reported-by: Sebastian Andrzej Siewior <[e-mail]>
Tested-by: Geert Uytterhoeven <[e-mail]>
Acked-by: John Stultz <[e-mail]>
Signed-off-by: Saravana Kannan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Reviewed-by: Rafael J. Wysocki <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>
Signed-off-by: Sasha Levin <[e-mail]>
---
 drivers/base/dd.c | 5 -----
 1 file changed, 5 deletions(-)

Patch

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index ed02a529a896..d6980f33afc4 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -257,7 +257,6 @@  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)
 {
@@ -312,7 +311,6 @@  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);
 
@@ -716,9 +714,6 @@  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);