linux-kernel - Re: [PATCH] clockevents/drivers/timer-atmel-pit: fix double free

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Date:	Fri, 18 Mar 2016 09:20:03 +0100
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	<bigeasy@...utronix.de>, Thomas Gleixner <tglx@...utronix.de>
CC:	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-rt-users@...r.kernel.org>
Subject: Re: [PATCH] clockevents/drivers/timer-atmel-pit: fix double free_irq

Le 17/03/2016 21:09, Alexandre Belloni a écrit :
> clockevents_exchange_device() changes the state from detached to shutdown
> and so at that point the IRQ has not yet been requested.
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>

> ---
> 
> Hi Sebastian,
> 
> This patch fixes the last warning for preempt-rt on at91. It applies on
> v4.4.4-rt11. Note that the whome PIT/TCB mess will be fixed in another way in
> the mainline as we are reworking the tcb driver to avoid using the pit when
> booting.

Yes, it's the plan!

Thanks Alexandre. Bye.

> 
>  drivers/clocksource/timer-atmel-pit.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clocksource/timer-atmel-pit.c b/drivers/clocksource/timer-atmel-pit.c
> index a7abdb6638cd..7a40f7e88468 100644
> --- a/drivers/clocksource/timer-atmel-pit.c
> +++ b/drivers/clocksource/timer-atmel-pit.c
> @@ -46,6 +46,7 @@ struct pit_data {
>  	u32		cycle;
>  	u32		cnt;
>  	unsigned int	irq;
> +	bool		irq_requested;
>  	struct clk	*mck;
>  };
>  
> @@ -96,7 +97,10 @@ static int pit_clkevt_shutdown(struct clock_event_device *dev)
>  
>  	/* disable irq, leaving the clocksource active */
>  	pit_write(data->base, AT91_PIT_MR, (data->cycle - 1) | AT91_PIT_PITEN);
> -	free_irq(data->irq, data);
> +	if (data->irq_requested) {
> +		free_irq(data->irq, data);
> +		data->irq_requested = false;
> +	}
>  	return 0;
>  }
>  
> @@ -115,6 +119,8 @@ static int pit_clkevt_set_periodic(struct clock_event_device *dev)
>  	if (ret)
>  		panic(pr_fmt("Unable to setup IRQ\n"));
>  
> +	data->irq_requested = true;
> +
>  	/* update clocksource counter */
>  	data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR));
>  	pit_write(data->base, AT91_PIT_MR,
> 


-- 
Nicolas Ferre