This is a note to let you know that I've just added the patch titled
driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
driver-core-fix-wait_for_device_probe-deferred_probe.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 328c969650b7ecb222121fe6ee9cdacda7c24bd7
Author: Saravana Kannan <saravanak@xxxxxxxxxx>
Date: Fri Jun 3 13:31:37 2022 +0200
driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction
[ 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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
[2] - https://lore.kernel.org/lkml/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/
[3] - https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@xxxxxxxxxxxxx/
Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires")
Cc: John Stultz <jstultz@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Cc: Basil Eljuse <Basil.Eljuse@xxxxxxx>
Cc: Ferry Toth <fntoth@xxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Anders Roxell <anders.roxell@xxxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reported-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Acked-by: John Stultz <jstultz@xxxxxxxxxx>
Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220526034609.480766-2-saravanak@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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);
