docs: cgroup-v2: fix misc.events key format descriptiongrafted

In misc cgroup, misc.events does not output a simple "max" key. Instead,
each registered misc resource outputs a separate key suffixed with ".max"
(i.e., "<res>.max").
Update the documentation to clarify that the entry key is "<res>.max".

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Cheng Lingfei <chenglingfei@foxmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/net_utils.c b/lib/net_utils.c
new file mode 100644
index 000000000..215cda672
--- /dev/null
+++ b/lib/net_utils.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/string.h>
+#include <linux/if_ether.h>
+#include <linux/ctype.h>
+#include <linux/export.h>
+#include <linux/hex.h>
+
+bool mac_pton(const char *s, u8 *mac)
+{
+	int i;
+
+	if (strnlen(s, MAC_ADDR_STR_LEN) < MAC_ADDR_STR_LEN)
+		return false;
+
+	/* Don't dirty result unless string is valid MAC. */
+	for (i = 0; i < ETH_ALEN; i++) {
+		if (!isxdigit(s[i * 3]) || !isxdigit(s[i * 3 + 1]))
+			return false;
+		if (i != ETH_ALEN - 1 && s[i * 3 + 2] != ':')
+			return false;
+	}
+	for (i = 0; i < ETH_ALEN; i++) {
+		mac[i] = (hex_to_bin(s[i * 3]) << 4) | hex_to_bin(s[i * 3 + 1]);
+	}
+	return true;
+}
+EXPORT_SYMBOL(mac_pton);