On Mon, 2012-11-26 at 14:55 -0200, Herton Ronaldo Krzesinski wrote: > 3.5.7u1 -stable review patch. If anyone has any objections, please let me > know. > > ------------------ > > From: Colin Cross <ccr...@android.com> > > commit 9d7d6e363b06934221b81a859d509844c97380df upstream. > > read_persistent_clock uses a global variable, use a spinlock to > ensure non-atomic updates to the variable don't overlap and cause > time to move backwards. > > Signed-off-by: Colin Cross <ccr...@android.com> > Signed-off-by: R Sricharan <r.sricha...@ti.com> > Signed-off-by: Tony Lindgren <t...@atomide.com> > Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesin...@canonical.com> [...]
This is also missing from 3.4. I'm attaching the adjusted version for 3.2, which looks like it will work for 3.4. Ben. -- Ben Hutchings Never attribute to conspiracy what can adequately be explained by stupidity.
From: Colin Cross <ccr...@android.com>
Date: Mon, 8 Oct 2012 14:01:12 -0700
Subject: ARM: OMAP: counter: add locking to read_persistent_clock
commit 9d7d6e363b06934221b81a859d509844c97380df upstream.
read_persistent_clock uses a global variable, use a spinlock to
ensure non-atomic updates to the variable don't overlap and cause
time to move backwards.
Signed-off-by: Colin Cross <ccr...@android.com>
Signed-off-by: R Sricharan <r.sricha...@ti.com>
Signed-off-by: Tony Lindgren <t...@atomide.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
arch/arm/plat-omap/counter_32k.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -82,22 +82,29 @@ static void notrace omap_update_sched_cl
* nsecs and adds to a monotonically increasing timespec.
*/
static struct timespec persistent_ts;
-static cycles_t cycles, last_cycles;
+static cycles_t cycles;
static unsigned int persistent_mult, persistent_shift;
+static DEFINE_SPINLOCK(read_persistent_clock_lock);
+
void read_persistent_clock(struct timespec *ts)
{
unsigned long long nsecs;
- cycles_t delta;
- struct timespec *tsp = &persistent_ts;
+ cycles_t last_cycles;
+ unsigned long flags;
+
+ spin_lock_irqsave(&read_persistent_clock_lock, flags);
last_cycles = cycles;
cycles = timer_32k_base ? __raw_readl(timer_32k_base) : 0;
- delta = cycles - last_cycles;
- nsecs = clocksource_cyc2ns(delta, persistent_mult, persistent_shift);
+ nsecs = clocksource_cyc2ns(cycles - last_cycles,
+ persistent_mult, persistent_shift);
+
+ timespec_add_ns(&persistent_ts, nsecs);
+
+ *ts = persistent_ts;
- timespec_add_ns(tsp, nsecs);
- *ts = *tsp;
+ spin_unlock_irqrestore(&read_persistent_clock_lock, flags);
}
int __init omap_init_clocksource_32k(void)
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