Commit fce8dc5e authored Jul 12, 2017 by Geert Uytterhoeven Committed by Simon Horman Jul 29, 2017

ARM: shmobile: rcar-gen2: Fix deadlock in regulator quirk



Simon Horman reported that Koelsch and Lager hang during boot, and
bisected this to commit 1c3c5eab ("sched/core: Enable
might_sleep() and smp_processor_id() checks early").

The da9063/da9210 regulator quirk for R-Car Gen2 boards uses a bus
notifier, and unregisters the notifier when it is no longer needed.
However, a notifier must not be unregistered from within the call chain.

This bug went unnoticed, as blocking_notifier_chain_unregister() didn't
take the semaphore during early boot.  The aforementioned commit changed
that behavior, leading to a deadlock.

Fix this by removing the call to bus_unregister_notifier(), and keeping
local completion state instead.

Reported-by: Simon Horman <horms+renesas@verge.net.au>
Fixes: 663fbb52 ("ARM: shmobile: R-Car Gen2: Add da9063/da9210 regulator quirk")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

parent 2ea659a9

arch/arm/mach-shmobile/regulator-quirk-rcar-gen2.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -67,8 +67,12 @@ static int regulator_quirk_notify(struct notifier_block *nb,
		{
		struct device *dev = data;
		struct i2c_client *client;
		static bool done;
		u32 mon;

		if (done)
		return 0;

		mon = ioread32(irqc + IRQC_MONITOR);
		dev_dbg(dev, "%s: %ld, IRQC_MONITOR = 0x%x\n", __func__, action, mon);
		if (mon & REGULATOR_IRQ_MASK)
		@@ -99,7 +103,7 @@ static int regulator_quirk_notify(struct notifier_block *nb,
		remove:
		dev_info(dev, "IRQ2 is not asserted, removing quirk\n");

		bus_unregister_notifier(&i2c_bus_type, nb);
		done = true;
		iounmap(irqc);
		return 0;
		}

Admin message