[tip:timers/core] time: Add y2038 safe read_boot_clock64()

[tip-bot for Xunlei Pang]

Commit-ID:  9a806ddbb9a18c510e4acdcc828b9a87f5fd3aef
Gitweb:     http://git.kernel.org/tip/9a806ddbb9a18c510e4acdcc828b9a87f5fd3aef
Author:     Xunlei Pang <pang.xunlei@xxxxxxxxxx>
AuthorDate: Wed, 1 Apr 2015 20:34:21 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 3 Apr 2015 08:18:18 +0200

time: Add y2038 safe read_boot_clock64()

As part of addressing in-kernel y2038 issues, this patch adds
read_boot_clock64() and replaces all the call sites of
read_boot_clock() with this function. This is a __weak
implementation, which simply calls the existing y2038 unsafe
read_boot_clock().

This allows architecture specific implementations to be
converted independently, and eventually the y2038 unsafe
read_boot_clock() can be removed after all its architecture
specific implementations have been converted to
read_boot_clock64().

Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Xunlei Pang <pang.xunlei@xxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1427945681-29972-2-git-send-email-john.stultz@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/timekeeping.h |  1 +
 kernel/time/timekeeping.c   | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 5047b83..18d27a3 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -269,6 +269,7 @@ static inline bool has_persistent_clock(void)
 
 extern void read_persistent_clock(struct timespec *ts);
 extern void read_boot_clock(struct timespec *ts);
+extern void read_boot_clock64(struct timespec64 *ts);
 extern int update_persistent_clock(struct timespec now);
 
 
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5b12292..652e50a 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1188,6 +1188,14 @@ void __weak read_boot_clock(struct timespec *ts)
 	ts->tv_nsec = 0;
 }
 
+void __weak read_boot_clock64(struct timespec64 *ts64)
+{
+	struct timespec ts;
+
+	read_boot_clock(&ts);
+	*ts64 = timespec_to_timespec64(ts);
+}
+
 /*
  * timekeeping_init - Initializes the clocksource and common timekeeping values
  */
@@ -1209,8 +1217,7 @@ void __init timekeeping_init(void)
 	} else if (now.tv_sec || now.tv_nsec)
 		persistent_clock_exist = true;
 
-	read_boot_clock(&ts);
-	boot = timespec_to_timespec64(ts);
+	read_boot_clock64(&boot);
 	if (!timespec64_valid_strict(&boot)) {
 		pr_warn("WARNING: Boot clock returned invalid value!\n"
 			"         Check your CMOS/BIOS settings.\n");
--
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