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Message-ID: <20250221131750.0630c720@pumpkin>
Date: Fri, 21 Feb 2025 13:17:50 +0000
From: David Laight <david.laight.linux@...il.com>
To: Uday Shankar <ushankar@...estorage.com>
Cc: Breno Leitao <leitao@...ian.org>, Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Rafał Miłecki <rafal@...ecki.pl>, Simon Horman
<horms@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Johannes
Berg <johannes@...solutions.net>, Jonathan Corbet <corbet@....net>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-wireless@...r.kernel.org, linux-doc@...r.kernel.org, Michal
Swiatkowski <michal.swiatkowski@...ux.intel.com>
Subject: Re: [PATCH net-next v5 1/2] net, treewide: define and use
MAC_ADDR_STR_LEN
On Thu, 20 Feb 2025 18:29:20 -0700
Uday Shankar <ushankar@...estorage.com> wrote:
> There are a few places in the tree which compute the length of the
> string representation of a MAC address as 3 * ETH_ALEN - 1. Define a
> constant for this and use it where relevant. No functionality changes
> are expected.
The fact that you have to keep adding 1 or 2 is a good indication that
it really isn't a good idea.
David
>
> Signed-off-by: Uday Shankar <ushankar@...estorage.com>
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> Acked-by: Johannes Berg <johannes@...solutions.net>
> ---
> drivers/net/netconsole.c | 2 +-
> drivers/nvmem/brcm_nvram.c | 2 +-
> drivers/nvmem/layouts/u-boot-env.c | 2 +-
> include/linux/if_ether.h | 3 +++
> lib/net_utils.c | 4 +---
> net/mac80211/debugfs_sta.c | 7 ++++---
> 6 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index f77eddf221850fe2778cd479e49c91ad695aba3c..12699831e3c9fdbafd4862a339aea4ef04cf522b 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -721,7 +721,7 @@ static ssize_t remote_mac_store(struct config_item *item, const char *buf,
>
> if (!mac_pton(buf, remote_mac))
> goto out_unlock;
> - if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
> + if (buf[MAC_ADDR_STR_LEN] && buf[MAC_ADDR_STR_LEN] != '\n')
> goto out_unlock;
> memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
>
> diff --git a/drivers/nvmem/brcm_nvram.c b/drivers/nvmem/brcm_nvram.c
> index b810df727b446b1762a1851750f743e0de6e8788..b4cf245fb2467d281111001bb7ed8db5993a09b2 100644
> --- a/drivers/nvmem/brcm_nvram.c
> +++ b/drivers/nvmem/brcm_nvram.c
> @@ -100,7 +100,7 @@ static int brcm_nvram_read_post_process_macaddr(void *context, const char *id, i
> {
> u8 mac[ETH_ALEN];
>
> - if (bytes != 3 * ETH_ALEN - 1)
> + if (bytes != MAC_ADDR_STR_LEN)
> return -EINVAL;
>
> if (!mac_pton(buf, mac))
> diff --git a/drivers/nvmem/layouts/u-boot-env.c b/drivers/nvmem/layouts/u-boot-env.c
> index 731e6f4f12b2bf28e4547d128954a095545ad461..436426d4e8f910b51b92f88acddfbb40d374587a 100644
> --- a/drivers/nvmem/layouts/u-boot-env.c
> +++ b/drivers/nvmem/layouts/u-boot-env.c
> @@ -37,7 +37,7 @@ static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, i
> {
> u8 mac[ETH_ALEN];
>
> - if (bytes != 3 * ETH_ALEN - 1)
> + if (bytes != MAC_ADDR_STR_LEN)
> return -EINVAL;
>
> if (!mac_pton(buf, mac))
> diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
> index 8a9792a6427ad9cf58b50c79cbfe185615800dcb..61b7335aa037c7232a0caa45572043057c02dde3 100644
> --- a/include/linux/if_ether.h
> +++ b/include/linux/if_ether.h
> @@ -19,6 +19,9 @@
> #include <linux/skbuff.h>
> #include <uapi/linux/if_ether.h>
>
> +/* XX:XX:XX:XX:XX:XX */
> +#define MAC_ADDR_STR_LEN (3 * ETH_ALEN - 1)
> +
> static inline struct ethhdr *eth_hdr(const struct sk_buff *skb)
> {
> return (struct ethhdr *)skb_mac_header(skb);
> diff --git a/lib/net_utils.c b/lib/net_utils.c
> index 42bb0473fb22f977409f7a6792bb1340f4e911c3..215cda672fee1b5a029c2b61529c6813c0edab11 100644
> --- a/lib/net_utils.c
> +++ b/lib/net_utils.c
> @@ -7,11 +7,9 @@
>
> bool mac_pton(const char *s, u8 *mac)
> {
> - size_t maxlen = 3 * ETH_ALEN - 1;
> int i;
>
> - /* XX:XX:XX:XX:XX:XX */
> - if (strnlen(s, maxlen) < maxlen)
> + if (strnlen(s, MAC_ADDR_STR_LEN) < MAC_ADDR_STR_LEN)
> return false;
>
> /* Don't dirty result unless string is valid MAC. */
> diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
> index a67a9d3160086ac492d77092a0c8a74d2384b28c..a8948f4d983e5edee45d90ad267582657ed38e38 100644
> --- a/net/mac80211/debugfs_sta.c
> +++ b/net/mac80211/debugfs_sta.c
> @@ -457,11 +457,12 @@ static ssize_t link_sta_addr_read(struct file *file, char __user *userbuf,
> size_t count, loff_t *ppos)
> {
> struct link_sta_info *link_sta = file->private_data;
> - u8 mac[3 * ETH_ALEN + 1];
> + u8 mac[MAC_ADDR_STR_LEN + 2];
>
> snprintf(mac, sizeof(mac), "%pM\n", link_sta->pub->addr);
>
> - return simple_read_from_buffer(userbuf, count, ppos, mac, 3 * ETH_ALEN);
> + return simple_read_from_buffer(userbuf, count, ppos, mac,
> + MAC_ADDR_STR_LEN + 1);
> }
>
> LINK_STA_OPS(addr);
> @@ -1240,7 +1241,7 @@ void ieee80211_sta_debugfs_add(struct sta_info *sta)
> struct ieee80211_local *local = sta->local;
> struct ieee80211_sub_if_data *sdata = sta->sdata;
> struct dentry *stations_dir = sta->sdata->debugfs.subdir_stations;
> - u8 mac[3*ETH_ALEN];
> + u8 mac[MAC_ADDR_STR_LEN + 1];
>
> if (!stations_dir)
> return;
>
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