Re: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of clk_enable() on UP systems

Sasha Levin
2018-03-19T17:00:37Z

On Mon, Mar 19, 2018 at 10:55:16AM -0500, David Lechner wrote:
>On 03/19/2018 10:48 AM, Sasha Levin wrote:
>>From: David Lechner <david@lechnology.com>
>>
>>[ 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 <sboyd@codeaurora.org>
>>Signed-off-by: David Lechner <david@lechnology.com>
>>Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
>>---
>
>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.
>

I'll remove it, thanks David!

--

Thanks,
Sasha