Commit-ID: f695cf94837de53864180400cbac42cfa370426f
Gitweb: http://git.kernel.org/tip/f695cf94837de53864180400cbac42cfa370426f
Author: John Stultz <john.stultz@xxxxxxxxxx>
AuthorDate: Wed, 14 Mar 2012 16:38:15 -0700
Committer: John Stultz <john.stultz@xxxxxxxxxx>
CommitDate: Thu, 15 Mar 2012 18:17:54 -0700
time: Fix change_clocksource locking
change_clocksource() fails to grab locks or call timekeeping_update(),
which leaves a race window for time inconsistencies.
This adds proper locking and a call to timekeeping_update() to fix this.
CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
kernel/time/timekeeping.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 403c2a0..b53da5e 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -448,9 +448,12 @@ EXPORT_SYMBOL(timekeeping_inject_offset);
static int change_clocksource(void *data)
{
struct clocksource *new, *old;
+ unsigned long flags;
new = (struct clocksource *) data;
+ write_seqlock_irqsave(&timekeeper.lock, flags);
+
timekeeping_forward_now();
if (!new->enable || new->enable(new) == 0) {
old = timekeeper.clock;
@@ -458,6 +461,10 @@ static int change_clocksource(void *data)
if (old->disable)
old->disable(old);
}
+ timekeeping_update(true);
+
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);
+
return 0;
}
--
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