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driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction
[ Upstream commit5ee76c256e
] 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. Commit35a672363a
("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/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/ [3] - https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@linutronix.de/ Fixes:35a672363a
("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>
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1 changed files with 0 additions and 5 deletions
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@ -257,7 +257,6 @@ DEFINE_SHOW_ATTRIBUTE(deferred_devs);
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int driver_deferred_probe_timeout;
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EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
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static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
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static int __init deferred_probe_timeout_setup(char *str)
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{
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@ -312,7 +311,6 @@ static void deferred_probe_timeout_work_func(struct work_struct *work)
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list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
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dev_info(p->device, "deferred probe pending\n");
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mutex_unlock(&deferred_probe_mutex);
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wake_up_all(&probe_timeout_waitqueue);
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}
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static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
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@ -716,9 +714,6 @@ int driver_probe_done(void)
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*/
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void wait_for_device_probe(void)
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{
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/* wait for probe timeout */
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wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
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/* wait for the deferred probe workqueue to finish */
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flush_work(&deferred_probe_work);
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