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authorDavid Vrabel <david.vrabel@citrix.com>2013-06-27 11:35:46 +0100
committerThomas Gleixner <tglx@linutronix.de>2013-06-28 23:15:06 +0200
commit780427f0e113b4c77dfff4d258c05a902cdb0eb9 (patch)
tree778bc50cbd83b67bdd6ae580a192c4c65e9711bd /kernel
parent04397fe94ad65289884b9862b6a0c722ececaadf (diff)
downloadlinux-780427f0e113b4c77dfff4d258c05a902cdb0eb9.tar.gz
linux-780427f0e113b4c77dfff4d258c05a902cdb0eb9.tar.xz
timekeeping: Indicate that clock was set in the pvclock gtod notifier
If the clock was set (stepped), set the action parameter to functions in the pvclock gtod notifier chain to non-zero. This allows the callee to only do work if the clock was stepped. This will be used on Xen as the synchronization of the Xen wallclock to the control domain's (dom0) system time will be done with this notifier and updating on every timer tick is unnecessary and too expensive. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: John Stultz <john.stultz@linaro.org> Cc: <xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/1372329348-20841-4-git-send-email-david.vrabel@citrix.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c30
1 files changed, 18 insertions, 12 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index d8b23a929e66..846d0a1f235e 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -29,6 +29,7 @@
#define TK_CLEAR_NTP (1 << 0)
#define TK_MIRROR (1 << 1)
+#define TK_CLOCK_WAS_SET (1 << 2)
static struct timekeeper timekeeper;
static DEFINE_RAW_SPINLOCK(timekeeper_lock);
@@ -204,9 +205,9 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
-static void update_pvclock_gtod(struct timekeeper *tk)
+static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
{
- raw_notifier_call_chain(&pvclock_gtod_chain, 0, tk);
+ raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
}
/**
@@ -220,7 +221,7 @@ int pvclock_gtod_register_notifier(struct notifier_block *nb)
raw_spin_lock_irqsave(&timekeeper_lock, flags);
ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
- update_pvclock_gtod(tk);
+ update_pvclock_gtod(tk, true);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return ret;
@@ -252,7 +253,7 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
ntp_clear();
}
update_vsyscall(tk);
- update_pvclock_gtod(tk);
+ update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
if (action & TK_MIRROR)
memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
@@ -512,7 +513,7 @@ int do_settimeofday(const struct timespec *tv)
tk_set_xtime(tk, tv);
- timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR);
+ timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -556,7 +557,7 @@ int timekeeping_inject_offset(struct timespec *ts)
tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
error: /* even if we error out, we forwarded the time, so call update */
- timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR);
+ timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -646,7 +647,7 @@ static int change_clocksource(void *data)
module_put(new->owner);
}
}
- timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR);
+ timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -887,7 +888,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
__timekeeping_inject_sleeptime(tk, delta);
- timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR);
+ timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -969,7 +970,7 @@ static void timekeeping_resume(void)
tk->cycle_last = clock->cycle_last = cycle_now;
tk->ntp_error = 0;
timekeeping_suspended = 0;
- timekeeping_update(tk, TK_MIRROR);
+ timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -1243,9 +1244,10 @@ out_adjust:
* It also calls into the NTP code to handle leapsecond processing.
*
*/
-static inline void accumulate_nsecs_to_secs(struct timekeeper *tk)
+static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
{
u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
+ unsigned int action = 0;
while (tk->xtime_nsec >= nsecps) {
int leap;
@@ -1268,8 +1270,10 @@ static inline void accumulate_nsecs_to_secs(struct timekeeper *tk)
__timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
clock_was_set_delayed();
+ action = TK_CLOCK_WAS_SET;
}
}
+ return action;
}
/**
@@ -1354,6 +1358,7 @@ static void update_wall_time(void)
struct timekeeper *tk = &shadow_timekeeper;
cycle_t offset;
int shift = 0, maxshift;
+ unsigned int action;
unsigned long flags;
raw_spin_lock_irqsave(&timekeeper_lock, flags);
@@ -1406,7 +1411,7 @@ static void update_wall_time(void)
* Finally, make sure that after the rounding
* xtime_nsec isn't larger than NSEC_PER_SEC
*/
- accumulate_nsecs_to_secs(tk);
+ action = accumulate_nsecs_to_secs(tk);
write_seqcount_begin(&timekeeper_seq);
/* Update clock->cycle_last with the new value */
@@ -1422,7 +1427,7 @@ static void update_wall_time(void)
* updating.
*/
memcpy(real_tk, tk, sizeof(*tk));
- timekeeping_update(real_tk, 0);
+ timekeeping_update(real_tk, action);
write_seqcount_end(&timekeeper_seq);
out:
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -1684,6 +1689,7 @@ int do_adjtimex(struct timex *txc)
if (tai != orig_tai) {
__timekeeping_set_tai_offset(tk, tai);
+ update_pvclock_gtod(tk, true);
clock_was_set_delayed();
}
write_seqcount_end(&timekeeper_seq);