linux-kernel - Re: [PATCH 03/34] brcmfmac: firmware: Support having multiple alt paths

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Message-ID: <c79d67af-2d4c-2c9d-bb7d-630faf9de175@gmail.com>
Date:   Sun, 2 Jan 2022 10:08:30 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Hector Martin <marcan@...can.st>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Arend van Spriel <aspriel@...il.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-hsien Lin <chi-hsien.lin@...ineon.com>,
        Wright Feng <wright.feng@...ineon.com>,
        Chung-hsien Hsu <chung-hsien.hsu@...ineon.com>
Cc:     Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Mark Kettenis <kettenis@...nbsd.org>,
        Rafał Miłecki <zajec5@...il.com>,
        Pieter-Paul Giesberts <pieter-paul.giesberts@...adcom.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Hans de Goede <hdegoede@...hat.com>,
        "John W. Linville" <linville@...driver.com>,
        "Daniel (Deognyoun) Kim" <dekim@...adcom.com>,
        "brian m. carlson" <sandals@...stytoothpaste.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, brcm80211-dev-list.pdl@...adcom.com,
        SHA-cyfmac-dev-list@...ineon.com
Subject: Re: [PATCH 03/34] brcmfmac: firmware: Support having multiple alt
 paths

26.12.2021 18:35, Hector Martin пишет:
> +static void brcm_free_alt_fw_paths(const char **alt_paths)
> +{
> +	int i;
> +
> +	if (!alt_paths)
> +		return;
> +
> +	for (i = 0; alt_paths[i]; i++)
> +		kfree(alt_paths[i]);
> +
> +	kfree(alt_paths);
>  }
>  
>  static int brcmf_fw_request_firmware(const struct firmware **fw,
>  				     struct brcmf_fw *fwctx)
>  {
>  	struct brcmf_fw_item *cur = &fwctx->req->items[fwctx->curpos];
> -	int ret;
> +	int ret, i;
>  
>  	/* Files can be board-specific, first try a board-specific path */
>  	if (cur->type == BRCMF_FW_TYPE_NVRAM && fwctx->req->board_type) {
> -		char *alt_path;
> +		const char **alt_paths = brcm_alt_fw_paths(cur->path, fwctx);
>  
> -		alt_path = brcm_alt_fw_path(cur->path, fwctx->req->board_type);
> -		if (!alt_path)
> +		if (!alt_paths)
>  			goto fallback;
>  
> -		ret = request_firmware(fw, alt_path, fwctx->dev);
> -		kfree(alt_path);
> -		if (ret == 0)
> -			return ret;
> +		for (i = 0; alt_paths[i]; i++) {
> +			ret = firmware_request_nowarn(fw, alt_paths[i], fwctx->dev);
> +			if (ret == 0) {
> +				brcm_free_alt_fw_paths(alt_paths);
> +				return ret;
> +			}
> +		}
> +		brcm_free_alt_fw_paths(alt_paths);
>  	}
>  
>  fallback:
> @@ -641,6 +663,9 @@ static void brcmf_fw_request_done(const struct firmware *fw, void *ctx)
>  	struct brcmf_fw *fwctx = ctx;
>  	int ret;
>  
> +	brcm_free_alt_fw_paths(fwctx->alt_paths);
> +	fwctx->alt_paths = NULL;

It looks suspicious that fwctx->alt_paths isn't zero'ed by other code
paths. The brcm_free_alt_fw_paths() should take fwctx for the argument
and fwctx->alt_paths should be set to NULL there.

On the other hand, I'd change the **alt_paths to a fixed-size array.
This should simplify the code, making it easier to follow and maintain.

-	const char **alt_paths;
+	char *alt_paths[BRCM_MAX_ALT_FW_PATHS];

Then you also won't need to NULL-terminate the array, which is a common
source of bugs in kernel.