netdev - RE: [RFC PATCH V3 net-next 5/5] ethtool: Add fallback to get_module

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Date:   Mon, 15 Mar 2021 15:31:10 -0700
From:   "Don Bollinger" <don@...bollingers.org>
To:     "'Moshe Shemesh'" <moshe@...dia.com>,
        "'David S. Miller'" <davem@...emloft.net>,
        "'Jakub Kicinski'" <kuba@...nel.org>,
        "'Andrew Lunn'" <andrew@...n.ch>,
        "'Adrian Pop'" <pop.adrian61@...il.com>,
        "'Michal Kubecek'" <mkubecek@...e.cz>, <netdev@...r.kernel.org>,
        <don@...bollingers.org>
Cc:     "'Vladyslav Tarasiuk'" <vladyslavt@...dia.com>
Subject: RE: [RFC PATCH V3 net-next 5/5] ethtool: Add fallback to get_module_eeprom from netlink command

On Mon, 15 Mar 2021 10:12:39 +0700 Moshe Shemesh wrote:
> From: Vladyslav Tarasiuk <vladyslavt@...dia.com>
> 
> In case netlink get_module_eeprom_data_by_page() callback is not
> implemented by the driver, try to call old get_module_info() and
> get_module_eeprom() pair. Recalculate parameters to
> get_module_eeprom() offset and len using page number and their sizes.
> Return error if this can't be done.
> 
> Signed-off-by: Vladyslav Tarasiuk <vladyslavt@...dia.com>
> ---
>  net/ethtool/eeprom.c | 75
> +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 74 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ethtool/eeprom.c b/net/ethtool/eeprom.c index
> e110336dc231..33ba9ecc36cb 100644
> --- a/net/ethtool/eeprom.c
> +++ b/net/ethtool/eeprom.c
> @@ -25,6 +25,79 @@ struct eeprom_data_reply_data {  #define
> EEPROM_DATA_REPDATA(__reply_base) \
>  	container_of(__reply_base, struct eeprom_data_reply_data, base)
> 
> +static int fallback_set_params(struct eeprom_data_req_info *request,
> +			       struct ethtool_modinfo *modinfo,
> +			       struct ethtool_eeprom *eeprom) {
> +	u32 offset = request->offset;
> +	u32 length = request->length;
> +
> +	if (request->page) {
> +		if (offset < 128 || offset + length >
> ETH_MODULE_EEPROM_PAGE_LEN)
> +			return -EINVAL;
> +		offset = request->page * 128 + offset;
> +	}
> +
> +	if (modinfo->type == ETH_MODULE_SFF_8079 &&
> +	    request->i2c_address == 0x51)
> +		offset += ETH_MODULE_EEPROM_PAGE_LEN;
> +
> +	if (!length)
> +		length = modinfo->eeprom_len;

Need to move this check up 11 lines, before the 'if (request->page)...'
stanza.  You need to be doing that check against the final length.
Otherwise you could have a request that includes a page, and a length of 0,
which becomes a length of modinfo->eeprom_len.

> +
> +	if (offset >= modinfo->eeprom_len)
> +		return -EINVAL;
> +
> +	if (modinfo->eeprom_len < offset + length)
> +		length = modinfo->eeprom_len - offset;
> +
> +	eeprom->cmd = ETHTOOL_GMODULEEEPROM;
> +	eeprom->len = length;
> +	eeprom->offset = offset;
> +
> +	return 0;
> +}
> +
> +static int eeprom_data_fallback(struct eeprom_data_req_info *request,
> +				struct eeprom_data_reply_data *reply,
> +				struct genl_info *info)
> +{
> +	struct net_device *dev = reply->base.dev;
> +	struct ethtool_modinfo modinfo = {0};
> +	struct ethtool_eeprom eeprom = {0};
> +	u8 *data;
> +	int err;
> +
> +	if ((!dev->ethtool_ops->get_module_info &&
> +	     !dev->ethtool_ops->get_module_eeprom) || request->bank) {
> +		return -EOPNOTSUPP;
> +	}
> +	modinfo.cmd = ETHTOOL_GMODULEINFO;
> +	err = dev->ethtool_ops->get_module_info(dev, &modinfo);
> +	if (err < 0)
> +		return err;
> +
> +	err = fallback_set_params(request, &modinfo, &eeprom);
> +	if (err < 0)
> +		return err;
> +
> +	data = kmalloc(eeprom.len, GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +	err = dev->ethtool_ops->get_module_eeprom(dev, &eeprom,
> data);
> +	if (err < 0)
> +		goto err_out;
> +
> +	reply->data = data;
> +	reply->length = eeprom.len;
> +
> +	return 0;
> +
> +err_out:
> +	kfree(data);
> +	return err;
> +}
> +
>  static int eeprom_data_prepare_data(const struct ethnl_req_info
> *req_base,
>  				    struct ethnl_reply_data *reply_base,
>  				    struct genl_info *info)
> @@ -36,7 +109,7 @@ static int eeprom_data_prepare_data(const struct
> ethnl_req_info *req_base,
>  	int ret;
> 
>  	if (!dev->ethtool_ops->get_module_eeprom_data_by_page)
> -		return -EOPNOTSUPP;
> +		return eeprom_data_fallback(request, reply, info);
> 
>  	page_data.offset = request->offset;
>  	page_data.length = request->length;
> --
> 2.26.2