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From: Shradha Gupta <shradhagupta@linux.microsoft.com>
To: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
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Cc: Shradha Gupta <shradhagupta@linux.microsoft.com>,
	shradhagupta@microsoft.com
Subject: [PATCH net-next v2 1/2] net: Add sysfs atttributes for max_mtu min_mtu
Date: Wed, 24 Apr 2024 03:33:37 -0700
Message-Id: <1713954817-30133-1-git-send-email-shradhagupta@linux.microsoft.com>
In-Reply-To: <1713954774-29953-1-git-send-email-shradhagupta@linux.microsoft.com>
References: <1713954774-29953-1-git-send-email-shradhagupta@linux.microsoft.com>
Precedence: bulk

Add sysfs attributes to read max_mtu and min_mtu value for
network devices

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
---
 Changes in v2:
 * Created a new patch for generic attributes
---
 Documentation/ABI/testing/sysfs-class-net | 16 ++++++++++++++++
 net/core/net-sysfs.c                      |  4 ++++
 2 files changed, 20 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net
index ebf21beba846..f68f3b9be6ec 100644
--- a/Documentation/ABI/testing/sysfs-class-net
+++ b/Documentation/ABI/testing/sysfs-class-net
@@ -352,3 +352,19 @@ Description:
 		0  threaded mode disabled for this dev
 		1  threaded mode enabled for this dev
 		== ==================================
+
+What:           /sys/class/net/<iface>/max_mtu
+Date:           April 2024
+KernelVersion:  6.10
+Contact:        netdev@vger.kernel.org
+Description:
+                Indicates the interface's maximum supported MTU value, in
+                bytes, and in decimal format.
+
+What:           /sys/class/net/<iface>/min_mtu
+Date:           April 2024
+KernelVersion:  6.10
+Contact:        netdev@vger.kernel.org
+Description:
+                Indicates the interface's minimum supported MTU value, in
+                bytes, and in decimal format.
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e3d7a8cfa20b..525b85d47676 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -114,6 +114,8 @@ NETDEVICE_SHOW_RO(addr_len, fmt_dec);
 NETDEVICE_SHOW_RO(ifindex, fmt_dec);
 NETDEVICE_SHOW_RO(type, fmt_dec);
 NETDEVICE_SHOW_RO(link_mode, fmt_dec);
+NETDEVICE_SHOW_RO(max_mtu, fmt_dec);
+NETDEVICE_SHOW_RO(min_mtu, fmt_dec);
 
 static ssize_t iflink_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
@@ -671,6 +673,8 @@ static struct attribute *net_class_attrs[] __ro_after_init = {
 	&dev_attr_carrier_up_count.attr,
 	&dev_attr_carrier_down_count.attr,
 	&dev_attr_threaded.attr,
+	&dev_attr_max_mtu.attr,
+	&dev_attr_min_mtu.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(net_class);
-- 
2.34.1