ICMP timestamp messages and IP source route options require
timestamps to be in milliseconds modulo 24 hours from
midnight UTC format.
Add a time function to support this. The function returns the
required timestamp in network byte order.
The function also uses y2038 safe time functions and data
structures.
Signed-off-by: Deepa Dinamani <deepa.ker...@gmail.com>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Alexey Kuznetsov <kuz...@ms2.inr.ac.ru>
Cc: James Morris <jmor...@namei.org>
Cc: Hideaki YOSHIFUJI <yoshf...@linux-ipv6.org>
Cc: Patrick McHardy <ka...@trash.net>
---
include/linux/ip.h | 2 ++
include/linux/time64.h | 3 +++
kernel/time/time.c | 26 ++++++++++++++++++++++++++
3 files changed, 31 insertions(+)
diff --git a/include/linux/ip.h b/include/linux/ip.h
index 492bc65..edf923e 100644
--- a/include/linux/ip.h
+++ b/include/linux/ip.h
@@ -34,4 +34,6 @@ static inline struct iphdr *ipip_hdr(const struct sk_buff
*skb)
{
return (struct iphdr *)skb_transport_header(skb);
}
+
+extern __be32 current_nw_timestamp(void);
#endif /* _LINUX_IP_H */
diff --git a/include/linux/time64.h b/include/linux/time64.h
index 367d5af..5b5db3b 100644
--- a/include/linux/time64.h
+++ b/include/linux/time64.h
@@ -35,6 +35,9 @@ struct itimerspec64 {
#define NSEC_PER_SEC 1000000000L
#define FSEC_PER_SEC 1000000000000000LL
+#define SECONDS_PER_DAY 86400
+#define MSEC_PER_DAY (SECONDS_PER_DAY * MSEC_PER_SEC)
+
/* Located here for timespec[64]_valid_strict */
#define TIME64_MAX ((s64)~((u64)1 << 63))
#define KTIME_MAX ((s64)~((u64)1 << 63))
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 86751c6..6df15df 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -245,6 +245,32 @@ struct timespec current_fs_time(struct super_block *sb)
EXPORT_SYMBOL(current_fs_time);
/*
+ * current_nw_timestamp - Return network time
+ *
+ * Return milliseconds since midnight in network byte order.
+ */
+__be32 current_nw_timestamp(void)
+{
+ u64 now;
+ u32 secs;
+ u32 msecs;
+ struct timespec64 ts;
+
+ ktime_get_ts64(&ts);
+
+ /* Get secs since midnight. */
+ now = div_u64_rem(ts.tv_sec, SECONDS_PER_DAY, &secs);
+ /* Convert to msecs. */
+ msecs = secs * MSEC_PER_SEC;
+ /* Convert nsec to msec. */
+ msecs += (u32)ts.tv_nsec/NSEC_PER_MSEC;
+
+ /* Convert to network byte order. */
+ return htons(msecs);
+}
+EXPORT_SYMBOL(current_nw_timestamp);
+
+/*
* Convert jiffies to milliseconds and back.
*
* Avoid unnecessary multiplications/divisions in the
--
1.9.1
