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authorLinus Torvalds <torvalds@linux-foundation.org>2010-08-06 13:12:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-06 13:12:36 -0700
commitaf390084359a5de20046c901529b2b6a50b941cb (patch)
treeb73a6261d1b1f9fb34432cc9a47411a49330b8dc /kernel/timer.c
parent7645e4320497b35ce9fb6c2269ebcd57af9fe735 (diff)
parent0fcb80818bc3ade5befd409051089f710adcf7b0 (diff)
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Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: Documentation: Add timers/timers-howto.txt timer: Added usleep_range timer Revert "timer: Added usleep[_range] timer" clockevents: Remove the per cpu tick skew posix_timer: Move copy_to_user(created_timer_id) down in timer_create() timer: Added usleep[_range] timer timers: Document meaning of deferrable timer
Diffstat (limited to 'kernel/timer.c')
-rw-r--r--kernel/timer.c31
1 files changed, 29 insertions, 2 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index d61d16da0b64..f1b8afe1ad86 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -90,8 +90,13 @@ static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
/*
* Note that all tvec_bases are 2 byte aligned and lower bit of
- * base in timer_list is guaranteed to be zero. Use the LSB for
- * the new flag to indicate whether the timer is deferrable
+ * base in timer_list is guaranteed to be zero. Use the LSB to
+ * indicate whether the timer is deferrable.
+ *
+ * A deferrable timer will work normally when the system is busy, but
+ * will not cause a CPU to come out of idle just to service it; instead,
+ * the timer will be serviced when the CPU eventually wakes up with a
+ * subsequent non-deferrable timer.
*/
#define TBASE_DEFERRABLE_FLAG (0x1)
@@ -1758,3 +1763,25 @@ unsigned long msleep_interruptible(unsigned int msecs)
}
EXPORT_SYMBOL(msleep_interruptible);
+
+static int __sched do_usleep_range(unsigned long min, unsigned long max)
+{
+ ktime_t kmin;
+ unsigned long delta;
+
+ kmin = ktime_set(0, min * NSEC_PER_USEC);
+ delta = (max - min) * NSEC_PER_USEC;
+ return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
+}
+
+/**
+ * usleep_range - Drop in replacement for udelay where wakeup is flexible
+ * @min: Minimum time in usecs to sleep
+ * @max: Maximum time in usecs to sleep
+ */
+void usleep_range(unsigned long min, unsigned long max)
+{
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ do_usleep_range(min, max);
+}
+EXPORT_SYMBOL(usleep_range);