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From:   Andreas Schwab <schwab@linux-m68k.org>
To:     YueHaibing <yuehaibing@huawei.com>
Cc:     <peppe.cavallaro@st.com>, <alexandre.torgue@st.com>,
        <joabreu@synopsys.com>, <davem@davemloft.net>, <kuba@kernel.org>,
        <mcoquelin.stm32@gmail.com>, <ajayg@nvidia.com>,
        <netdev@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: stmmac: Fix signedness bug in
 stmmac_probe_config_dt()
References: <20200818143952.50752-1-yuehaibing@huawei.com>
Date:   Tue, 18 Aug 2020 16:51:56 +0200
In-Reply-To: <20200818143952.50752-1-yuehaibing@huawei.com>
        (yuehaibing@huawei.com's message of "Tue, 18 Aug 2020 22:39:52 +0800")
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On Aug 18 2020, YueHaibing wrote:

> The "plat->phy_interface" variable is an enum and in this context GCC
> will treat it as an unsigned int so the error handling is never
> triggered.
>
> Fixes: b9f0b2f634c0 ("net: stmmac: platform: fix probe for ACPI devices")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index f32317fa75c8..b5b558b02e7d 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -413,7 +413,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
>  	}
>  
>  	plat->phy_interface = device_get_phy_mode(&pdev->dev);
> -	if (plat->phy_interface < 0)
> +	if ((int)plat->phy_interface < 0)
>  		return ERR_PTR(plat->phy_interface);

I don't think the conversion to long when passed to ERR_PTR will produce
a negative value either (if long is wider than unsigned int).

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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