linux-kernel - Re: [PATCH] brcmfmac: Transform compatible string for FW loading

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Date:   Thu, 25 Jun 2020 19:09:19 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     matthias.bgg@...nel.org, arend.vanspriel@...adcom.com,
        kvalo@...eaurora.org, davem@...emloft.net, kuba@...nel.org
Cc:     franky.lin@...adcom.com, hante.meuleman@...adcom.com,
        chi-hsien.lin@...ress.com, wright.feng@...ress.com,
        mbrugger@...e.com, linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] brcmfmac: Transform compatible string for FW loading

Hi,

On 6/25/20 6:07 PM, matthias.bgg@...nel.org wrote:
> From: Matthias Brugger <mbrugger@...e.com>
> 
> The driver relies on the compatible string from DT to determine which
> FW configuration file it should load. The DTS spec allows for '/' as
> part of the compatible string. We change this to '-' so that we will
> still be able to load the config file, even when the compatible has a
> '/'. This fixes explicitly the firmware loading for
> "solidrun,cubox-i/q".
> 
> Signed-off-by: Matthias Brugger <mbrugger@...e.com>
> ---
>   .../wireless/broadcom/brcm80211/brcmfmac/of.c  | 18 +++++++++++++++---
>   1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> index b886b56a5e5a..8a41b7f9cad3 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> @@ -17,7 +17,6 @@ void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
>   {
>   	struct brcmfmac_sdio_pd *sdio = &settings->bus.sdio;
>   	struct device_node *root, *np = dev->of_node;
> -	struct property *prop;
>   	int irq;
>   	u32 irqf;
>   	u32 val;
> @@ -25,8 +24,21 @@ void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
>   	/* Set board-type to the first string of the machine compatible prop */
>   	root = of_find_node_by_path("/");
>   	if (root) {
> -		prop = of_find_property(root, "compatible", NULL);
> -		settings->board_type = of_prop_next_string(prop, NULL);
> +		int i;
> +		char *board_type;
> +		const char *tmp;
> +
> +		of_property_read_string_index(root, "compatible", 0, &tmp);
> +
> +		/* get rid of '/' in the compatible string to be able to find the FW */
> +		board_type = devm_kzalloc(dev, strlen(tmp), GFP_KERNEL);

strlen() needs to be strlen() + 1 here to make place for the terminating zero.

> +		strncpy(board_type, tmp, strlen(tmp));

Please do not us strncpy, it is THE worst strcpy function
in existence, it does not guarantee 0 termination, so
it sucks, it sucks a lot do not use, thanks.

Instead use strlcpy or snprintf(..., "%s", ...)

> +		for (i = 0; i < strlen(board_type); i++) {

(The strlen here relies on there being a 0 behind the memory you
allocated because of the missing + 1)

> +			if (board_type[i] == '/')
> +				board_type[i] = '-';
> +		}
> +		settings->board_type = board_type;
> +
>   		of_node_put(root);
>   	}
>   
> 

Otherwise this looks good to me.

Regards,

Hans