Re: [PATCH] gpu: host1x: fix uninitialized variable use

From: Nick Desaulniers <ndesaulniers@google.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Arnd Bergmann <arnd@arndb.de>,
	Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>,
	Mikko Perttunen <mperttunen@nvidia.com>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	Robin Murphy <robin.murphy@arm.com>,
	dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH] gpu: host1x: fix uninitialized variable use
Date: Wed, 1 Feb 2023 15:19:31 -0800	[thread overview]
Message-ID: <Y9rzg9Mizckjf+Fp@google.com> (raw)
In-Reply-To: <20230127221418.2522612-1-arnd@kernel.org>

On Fri, Jan 27, 2023 at 11:14:00PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The error handling for platform_get_irq() failing no longer
> works after a recent change, clang now points this out with
> a warning:
> 
> drivers/gpu/host1x/dev.c:520:6: error: variable 'syncpt_irq' is uninitialized when used here [-Werror,-Wuninitialized]
>         if (syncpt_irq < 0)
>             ^~~~~~~~~~
> 
> Fix this by removing the variable and checking the correct
> error status.
> 
> Fixes: 625d4ffb438c ("gpu: host1x: Rewrite syncpoint interrupt handling")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks Arnd, I saw some reports from kernelci about this, too.
https://lore.kernel.org/linux-next/?q=warning%3A+variable+%27syncpt_irq%27+is+uninitialized+when+used+here

Reported-by: "kernelci.org bot" <bot@kernelci.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  drivers/gpu/host1x/dev.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
> index 4872d183d860..aae2efeef503 100644
> --- a/drivers/gpu/host1x/dev.c
> +++ b/drivers/gpu/host1x/dev.c
> @@ -487,7 +487,6 @@ static int host1x_get_resets(struct host1x *host)
>  static int host1x_probe(struct platform_device *pdev)
>  {
>  	struct host1x *host;
> -	int syncpt_irq;
>  	int err;
>  
>  	host = devm_kzalloc(&pdev->dev, sizeof(*host), GFP_KERNEL);
> @@ -517,8 +516,8 @@ static int host1x_probe(struct platform_device *pdev)
>  	}
>  
>  	host->syncpt_irq = platform_get_irq(pdev, 0);
> -	if (syncpt_irq < 0)
> -		return syncpt_irq;
> +	if (host->syncpt_irq < 0)
> +		return host->syncpt_irq;
>  
>  	mutex_init(&host->devices_lock);
>  	INIT_LIST_HEAD(&host->devices);
> -- 
> 2.39.0
> 
> 