linux-kernel - Re: [PATCH v1 1/1] usb: gadget: Move kstrtox() out of lock

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Message-ID: <Y8rqu7osxWsdN/PA@donbot>
Date:   Fri, 20 Jan 2023 19:25:47 +0000
From:   John Keeping <john@...anate.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jó Ágila Bitsch <jgilab@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] usb: gadget: Move kstrtox() out of lock

On Fri, Jan 20, 2023 at 08:24:34PM +0200, Andy Shevchenko wrote:
> The kstrtox() calls operate on local (to the function) variables and do
> not need to be serialized. We may call them out of the lock.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Reviewed-by: John Keeping <john@...anate.com>

> ---
>  drivers/usb/gadget/configfs.c | 72 +++++++++++++++++------------------
>  1 file changed, 36 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> index 78e7353e397b..63dc15b4f6d8 100644
> --- a/drivers/usb/gadget/configfs.c
> +++ b/drivers/usb/gadget/configfs.c
> @@ -808,15 +808,15 @@ static ssize_t webusb_use_store(struct config_item *item, const char *page,
>  	int ret;
>  	bool use;
>  
> -	mutex_lock(&gi->lock);
>  	ret = kstrtobool(page, &use);
> -	if (!ret) {
> -		gi->use_webusb = use;
> -		ret = len;
> -	}
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&gi->lock);
> +	gi->use_webusb = use;
>  	mutex_unlock(&gi->lock);
>  
> -	return ret;
> +	return len;
>  }
>  
>  static ssize_t webusb_bcdVersion_show(struct config_item *item, char *page)
> @@ -832,10 +832,12 @@ static ssize_t webusb_bcdVersion_store(struct config_item *item,
>  	u16 bcdVersion;
>  	int ret;
>  
> -	mutex_lock(&gi->lock);
>  	ret = kstrtou16(page, 0, &bcdVersion);
>  	if (ret)
> -		goto out;
> +		return ret;
> +
> +	mutex_lock(&gi->lock);
> +
>  	ret = is_valid_bcd(bcdVersion);
>  	if (ret)
>  		goto out;
> @@ -862,15 +864,15 @@ static ssize_t webusb_bVendorCode_store(struct config_item *item,
>  	int ret;
>  	u8 b_vendor_code;
>  
> -	mutex_lock(&gi->lock);
>  	ret = kstrtou8(page, 0, &b_vendor_code);
> -	if (!ret) {
> -		gi->b_webusb_vendor_code = b_vendor_code;
> -		ret = len;
> -	}
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&gi->lock);
> +	gi->b_webusb_vendor_code = b_vendor_code;
>  	mutex_unlock(&gi->lock);
>  
> -	return ret;
> +	return len;
>  }
>  
>  static ssize_t webusb_landingPage_show(struct config_item *item, char *page)
> @@ -956,15 +958,15 @@ static ssize_t os_desc_use_store(struct config_item *item, const char *page,
>  	int ret;
>  	bool use;
>  
> -	mutex_lock(&gi->lock);
>  	ret = kstrtobool(page, &use);
> -	if (!ret) {
> -		gi->use_os_desc = use;
> -		ret = len;
> -	}
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&gi->lock);
> +	gi->use_os_desc = use;
>  	mutex_unlock(&gi->lock);
>  
> -	return ret;
> +	return len;
>  }
>  
>  static ssize_t os_desc_b_vendor_code_show(struct config_item *item, char *page)
> @@ -980,15 +982,15 @@ static ssize_t os_desc_b_vendor_code_store(struct config_item *item,
>  	int ret;
>  	u8 b_vendor_code;
>  
> -	mutex_lock(&gi->lock);
>  	ret = kstrtou8(page, 0, &b_vendor_code);
> -	if (!ret) {
> -		gi->b_vendor_code = b_vendor_code;
> -		ret = len;
> -	}
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&gi->lock);
> +	gi->b_vendor_code = b_vendor_code;
>  	mutex_unlock(&gi->lock);
>  
> -	return ret;
> +	return len;
>  }
>  
>  static ssize_t os_desc_qw_sign_show(struct config_item *item, char *page)
> @@ -1113,15 +1115,15 @@ static ssize_t ext_prop_type_store(struct config_item *item,
>  	u8 type;
>  	int ret;
>  
> -	if (desc->opts_mutex)
> -		mutex_lock(desc->opts_mutex);
>  	ret = kstrtou8(page, 0, &type);
>  	if (ret)
> -		goto end;
> -	if (type < USB_EXT_PROP_UNICODE || type > USB_EXT_PROP_UNICODE_MULTI) {
> -		ret = -EINVAL;
> -		goto end;
> -	}
> +		return ret;
> +
> +	if (type < USB_EXT_PROP_UNICODE || type > USB_EXT_PROP_UNICODE_MULTI)
> +		return -EINVAL;
> +
> +	if (desc->opts_mutex)
> +		mutex_lock(desc->opts_mutex);
>  
>  	if ((ext_prop->type == USB_EXT_PROP_BINARY ||
>  	    ext_prop->type == USB_EXT_PROP_LE32 ||
> @@ -1138,12 +1140,10 @@ static ssize_t ext_prop_type_store(struct config_item *item,
>  		   type == USB_EXT_PROP_BE32))
>  		ext_prop->data_len >>= 1;
>  	ext_prop->type = type;
> -	ret = len;
>  
> -end:
>  	if (desc->opts_mutex)
>  		mutex_unlock(desc->opts_mutex);
> -	return ret;
> +	return len;
>  }
>  
>  static ssize_t ext_prop_data_show(struct config_item *item, char *page)
> -- 
> 2.39.0
>