[PATCH] ARM: SAMSUNG: Bug fix spin_lock recursion in clk_enable() and clk_disable()

Ben Dooks
2010-10-18T23:09:25Z

On 12/10/10 01:39, Jaecheol Lee wrote:
> From: Minho Ban <mhban@samsung.com>
>
> The clk_enable() and clk_disable() can be used process and ISR either.
> So spin_lock_irqsave should be used instead.
>
> Signed-off-by: Minho Ban <mhban@samsung.com>
> Signed-off-by: Jaecheol Lee <jc.lee@samsung.com>
> ---
> arch/arm/plat-samsung/clock.c | 12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/plat-samsung/clock.c b/arch/arm/plat-samsung/clock.c
> index e8d20b0..2a991a5 100644
> --- a/arch/arm/plat-samsung/clock.c
> +++ b/arch/arm/plat-samsung/clock.c
> @@ -138,31 +138,35 @@ void clk_put(struct clk *clk)
>
> int clk_enable(struct clk *clk)
> {
> + unsigned long flags;
> +
> if (IS_ERR(clk) || clk == NULL)
> return -EINVAL;
>
> clk_enable(clk->parent);
>
> - spin_lock(&clocks_lock);
> + spin_lock_irqsave(&clocks_lock, flags);
>
> if ((clk->usage++) == 0)
> (clk->enable)(clk, 1);
>
> - spin_unlock(&clocks_lock);
> + spin_unlock_irqrestore(&clocks_lock, flags);
> return 0;
> }
>
> void clk_disable(struct clk *clk)
> {
> + unsigned long flags;
> +
> if (IS_ERR(clk) || clk == NULL)
> return;
>
> - spin_lock(&clocks_lock);
> + spin_lock_irqsave(&clocks_lock, flags);
>
> if ((--clk->usage) == 0)
> (clk->enable)(clk, 0);
>
> - spin_unlock(&clocks_lock);
> + spin_unlock_irqrestore(&clocks_lock, flags);
> clk_disable(clk->parent);

I'm not sure, but I don't belive that the clk_ api has
ever been callable from non-sleepable contexts such as
interrupt handlers.

I would welcome RMK's response (or any other response)
about this issue?

Personally, given that some clk_ calls may sleep esp.
for pll enables, I would prefer to see this patch
dropped in favour of fixing the users.

--
Ben