linux-kernel - Re: [PATCH v2] clk: fix reentrancy of clk

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Date:   Wed, 10 Jan 2018 13:40:44 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     David Lechner <david@...hnology.com>
Cc:     linux-clk@...r.kernel.org,
        Michael Turquette <mturquette@...libre.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: fix reentrancy of clk_enable() on UP systems

On 01/04, David Lechner wrote:
> 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>
> ---

Applied to clk-next

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