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Commit 38a8914f authored by Will Deacon's avatar Will Deacon Committed by Russell King
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ARM: 6987/1: l2x0: fix disabling function to avoid deadlock 



The l2x0_disable function attempts to writel with the l2x0_lock held.
This results in deadlock when the writel contains an outer_sync call
for the platform since the l2x0_lock is already held by the disable
function. A further problem is that disabling the L2 without flushing it
first can lead to the spin_lock operation becoming visible after the
spin_unlock, causing any subsequent L2 maintenance to deadlock.

This patch replaces the writel with a call to writel_relaxed in the
disabling code and adds a flush before disabling in the control
register, preventing livelock from occurring.

Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 186dcaa4

arch/arm/mm/cache-l2x0.c

+13 −6
Original line number Diff line number Diff line
@@ -120,17 +120,22 @@ static void l2x0_cache_sync(void) 
	spin_unlock_irqrestore(&l2x0_lock, flags);

}



static void l2x0_flush_all(void)

static void __l2x0_flush_all(void)

{

	unsigned long flags;



	/* clean all ways */

	spin_lock_irqsave(&l2x0_lock, flags);

	debug_writel(0x03);

	writel_relaxed(l2x0_way_mask, l2x0_base + L2X0_CLEAN_INV_WAY);

	cache_wait_way(l2x0_base + L2X0_CLEAN_INV_WAY, l2x0_way_mask);

	cache_sync();

	debug_writel(0x00);

}



static void l2x0_flush_all(void)

{

	unsigned long flags;



	/* clean all ways */

	spin_lock_irqsave(&l2x0_lock, flags);

	__l2x0_flush_all();

	spin_unlock_irqrestore(&l2x0_lock, flags);

}
@@ -266,7 +271,9 @@ static void l2x0_disable(void) 
	unsigned long flags;



	spin_lock_irqsave(&l2x0_lock, flags);

	writel(0, l2x0_base + L2X0_CTRL);

	__l2x0_flush_all();

	writel_relaxed(0, l2x0_base + L2X0_CTRL);

	dsb();

	spin_unlock_irqrestore(&l2x0_lock, flags);

}