linux-kernel - Re: [PATCH] carl9170: Fix error return -EAGAIN if not started

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Message-ID: <20211008055854.GE2048@kadam>
Date:   Fri, 8 Oct 2021 08:58:54 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Christian Lamparter <chunkeey@...glemail.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "John W . Linville" <linville@...driver.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] carl9170: Fix error return -EAGAIN if not started

On Fri, Oct 08, 2021 at 01:15:58AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> There is an error return path where the error return is being
> assigned to err rather than count and the error exit path does
> not return -EAGAIN as expected. Fix this by setting the error
> return to variable count as this is the value that is returned
> at the end of the function.
> 
> Addresses-Coverity: ("Unused value")
> Fixes: 00c4da27a421 ("carl9170: firmware parser and debugfs code")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/net/wireless/ath/carl9170/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/carl9170/debug.c b/drivers/net/wireless/ath/carl9170/debug.c
> index bb40889d7c72..f163c6bdac8f 100644
> --- a/drivers/net/wireless/ath/carl9170/debug.c
> +++ b/drivers/net/wireless/ath/carl9170/debug.c
> @@ -628,7 +628,7 @@ static ssize_t carl9170_debugfs_bug_write(struct ar9170 *ar, const char *buf,
>  
>  	case 'R':
>  		if (!IS_STARTED(ar)) {
> -			err = -EAGAIN;
> +			count = -EAGAIN;
>  			goto out;

This is ugly.  The bug wouldn't have happened with a direct return, it's
only the goto out which causes it.  Better to replace all the error
paths with direct returns.  There are two other direct returns so it's
not like a new thing...

Goto out on the success path is fine here, though.

regards,
dan carpenter