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authorJosh Boyer <jwboyer@fedoraproject.org>2013-09-20 11:18:49 -0400
committerJosh Boyer <jwboyer@fedoraproject.org>2013-09-20 16:22:32 -0400
commit12089cc748756d1eda72e1ad7ba630aefface4df (patch)
tree58b5a43d02e2ab998ca7a3ffaa2e7c363807e3b2
parentf2c5f4cfa6ab44132ec8a75400f76f5d78522d60 (diff)
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Fix RTC updates from ntp (rhbz 985522)
-rw-r--r--kernel.spec9
-rw-r--r--ntp-Make-periodic-RTC-update-more-reliable.patch44
2 files changed, 53 insertions, 0 deletions
diff --git a/kernel.spec b/kernel.spec
index cd236a5b2..08db63a3d 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -759,6 +759,9 @@ Patch25104: ansi_cprng-Fix-off-by-one-error-in-non-block-size-request.patch
Patch25103: fix-arm-btrfs-build.patch
+#rhbz 985522
+Patch25107: ntp-Make-periodic-RTC-update-more-reliable.patch
+
# END OF PATCH DEFINITIONS
%endif
@@ -1478,6 +1481,9 @@ ApplyPatch fix-arm-btrfs-build.patch
#CVE-2013-4345 rhbz 1007690 1009136
ApplyPatch ansi_cprng-Fix-off-by-one-error-in-non-block-size-request.patch
+#rhbz 985522
+ApplyPatch ntp-Make-periodic-RTC-update-more-reliable.patch
+
# END OF PATCH APPLICATIONS
%endif
@@ -2282,6 +2288,9 @@ fi
# ||----w |
# || ||
%changelog
+* Fri Sep 20 2013 Josh Boyer <jwboyer@fedoraproject.org>
+- Fix RTC updates from ntp (rhbz 985522)
+
* Fri Sep 20 2013 Josh Boyer <jwboyer@fedoraproject.org> - 3.12.0-0.rc1.git4.1
- Linux v3.12-rc1-250-g7b9e3a6
diff --git a/ntp-Make-periodic-RTC-update-more-reliable.patch b/ntp-Make-periodic-RTC-update-more-reliable.patch
new file mode 100644
index 000000000..59179e719
--- /dev/null
+++ b/ntp-Make-periodic-RTC-update-more-reliable.patch
@@ -0,0 +1,44 @@
+From a97ad0c4b447a132a322cedc3a5f7fa4cab4b304 Mon Sep 17 00:00:00 2001
+From: Miroslav Lichvar <mlichvar@redhat.com>
+Date: Thu, 1 Aug 2013 19:31:35 +0200
+Subject: [PATCH] ntp: Make periodic RTC update more reliable
+
+The current code requires that the scheduled update of the RTC happens
+in the closest tick to the half of the second. This seems to be
+difficult to achieve reliably. The scheduled work may be missing the
+target time by a tick or two and be constantly rescheduled every second.
+
+Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute
+update interval by several milliseconds, this shouldn't affect the
+overall accuracy of the RTC much.
+
+Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
+Signed-off-by: John Stultz <john.stultz@linaro.org>
+---
+ kernel/time/ntp.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
+index 8f5b3b9..ab1fa7c 100644
+--- a/kernel/time/ntp.c
++++ b/kernel/time/ntp.c
+@@ -475,6 +475,7 @@ static void sync_cmos_clock(struct work_struct *work)
+ * called as close as possible to 500 ms before the new second starts.
+ * This code is run on a timer. If the clock is set, that timer
+ * may not expire at the correct time. Thus, we adjust...
++ * We want the clock to be within a couple of ticks from the target.
+ */
+ if (!ntp_synced()) {
+ /*
+@@ -485,7 +486,7 @@ static void sync_cmos_clock(struct work_struct *work)
+ }
+
+ getnstimeofday(&now);
+- if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) {
++ if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec * 5) {
+ struct timespec adjust = now;
+
+ fail = -ENODEV;
+--
+1.7.9.5
+