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    SubjectRe: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of clk_enable() on UP systems
    On 03/19/2018 10:48 AM, Sasha Levin wrote:
    > From: David Lechner <>
    > [ Upstream commit a12aa8a68dfef5de181f2e555aa950a0ab05411f ]
    > Reentrant calls to clk_enable() are not working on UP systems. This is
    > caused by the fact spin_trylock_irqsave() always returns true when
    > CONFIG_SMP=n (and CONFIG_DEBUG_SPINLOCK=n) which causes the reference
    > counting to not work correctly when clk_enable_lock() is called twice
    > before clk_enable_unlock() is called (this happens when clk_enable()
    > is called from within another clk_enable()).
    > This fixes the problem by skipping the call to spin_trylock_irqsave() on UP
    > systems and relying solely on reference counting. We also make sure to set
    > flags in this case so that we are not returning an uninitialized value.
    > Suggested-by: Stephen Boyd <>
    > Signed-off-by: David Lechner <>
    > Signed-off-by: Stephen Boyd <>
    > Signed-off-by: Sasha Levin <>
    > ---

    I don't know of any existing bugs in v4.15 that this fixes, so I don't
    think this really fits the criteria for stable.

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      Last update: 2018-03-19 23:05    [W:13.439 / U:0.008 seconds]
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