linux-kernel - Re: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of clk

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Message-ID: <20180403032740.GL7561@sasha-vm>
Date:   Tue, 3 Apr 2018 03:27:41 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     David Lechner <david@...hnology.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH AUTOSEL for 4.15 104/124] clk: fix reentrancy of
 clk_enable() on UP systems

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@...hnology.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@...eaurora.org>
>>Signed-off-by: David Lechner <david@...hnology.com>
>>Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
>>Signed-off-by: Sasha Levin <alexander.levin@...rosoft.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.
>

Now removed, thanks!