linux-kernel - Re: [PATCH] clocksource: nps: avoid maybe-uninitialized warning

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Message-ID: <375fd3c2-a037-afda-e77b-ba0f9654d36c@synopsys.com>
Date:   Tue, 22 Nov 2016 10:25:38 -0800
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Arnd Bergmann <arnd@...db.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     Noam Camus <noamca@...lanox.com>,
        Liviu Dudau <Liviu.Dudau@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clocksource: nps: avoid maybe-uninitialized warning

On 11/22/2016 06:34 AM, Arnd Bergmann wrote:
> We get a harmless false-positive warning with the newly added nps
> clocksource driver:
>
> drivers/clocksource/timer-nps.c: In function 'nps_setup_clocksource':
> drivers/clocksource/timer-nps.c:102:6: error: 'nps_timer1_freq' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> Gcc here fails to identify that IS_ERR() is only true if PTR_ERR()
> has a nonzero value. Using PTR_ERR_OR_ZERO() to convert the result
> first makes this obvious and shuts up the warning.
>
> Fixes: 0ee4d9922df5 ("clocksource: Add clockevent support to NPS400 driver")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Thx for this fix Arnd. Since the driver is going via my tree, I added it to the
patchset.

-Vineet

> ---
>  drivers/clocksource/timer-nps.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clocksource/timer-nps.c b/drivers/clocksource/timer-nps.c
> index b4c8a023a2d4..8da5e93b6810 100644
> --- a/drivers/clocksource/timer-nps.c
> +++ b/drivers/clocksource/timer-nps.c
> @@ -53,9 +53,10 @@ static int __init nps_get_timer_clk(struct device_node *node,
>  	int ret;
>  
>  	*clk = of_clk_get(node, 0);
> -	if (IS_ERR(*clk)) {
> +	ret = PTR_ERR_OR_ZERO(*clk);
> +	if (ret) {
>  		pr_err("timer missing clk");
> -		return PTR_ERR(*clk);
> +		return ret;
>  	}
>  
>  	ret = clk_prepare_enable(*clk);