Sometimes you want the waitqueue wake-up ignoring effect of msleep() or
msleep_interruptible(), but happen to know the desired timeout in
jiffies rather than milliseconds. In this case you'd do something like
this:
msleep(jiffies_to_msecs(timeout_in_jiffies));
The first thing that msleep() and msleep_interruptible() do is convert
the parameter to jiffies (and msleep_interruptible() converts its return
value back to milliseconds).
The new functions jsleep() and jsleep_interruptible() behave like
msleep() and msleep_interruptible() except that the desired timeout (and
return value of jsleep_interruptible()) is specified in jiffies. So the
above call could be simplified to:
jsleep(timeout_in_jiffies);
I'm not sure how useful this would be, but there are a couple of places
in "serial_core.c" that could usefully call jsleep_interruptible()
instead of msleep_interruptible().
Signed-off-by: Ian Abbott <abbo...@mev.co.uk>
---
Documentation/timers/timers-howto.txt | 11 +++++++++--
include/linux/delay.h | 2 ++
kernel/timer.c | 32 +++++++++++++++++++++++++++-----
3 files changed, 38 insertions(+), 7 deletions(-)
diff --git a/Documentation/timers/timers-howto.txt
b/Documentation/timers/timers-howto.txt
index 038f8c7..2911600 100644
--- a/Documentation/timers/timers-howto.txt
+++ b/Documentation/timers/timers-howto.txt
@@ -46,8 +46,11 @@ NON-ATOMIC CONTEXT:
-- Backed by hrtimers:
usleep_range(unsigned long min, unsigned long max)
-- Backed by jiffies / legacy_timers
- msleep(unsigned long msecs)
- msleep_interruptible(unsigned long msecs)
+ jsleep(unsigned long timeout)
+ jsleep_interruptible(unsigned long timeout)
+ msleep(unsigned int msecs)
+ msleep_interruptible(unsigned int msecs)
+ ssleep(unsigned int secs)
Unlike the *delay family, the underlying mechanism
driving each of these calls varies, thus there are
@@ -103,3 +106,7 @@ NON-ATOMIC CONTEXT:
short, the difference is whether the sleep can be ended
early by a signal. In general, just use msleep unless
you know you have a need for the interruptible variant.
+
+ If the required delay is in jiffies, jsleep and
+ jsleep_interruptible are good alternatives to msleep
+ and msleep_interruptible, respectively.
diff --git a/include/linux/delay.h b/include/linux/delay.h
index a6ecb34..dffa295 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -43,6 +43,8 @@ static inline void ndelay(unsigned long x)
extern unsigned long lpj_fine;
void calibrate_delay(void);
+void jsleep(unsigned long timeout);
+unsigned long jsleep_interruptible(unsigned long timeout);
void msleep(unsigned int msecs);
unsigned long msleep_interruptible(unsigned int msecs);
void usleep_range(unsigned long min, unsigned long max);
diff --git a/kernel/timer.c b/kernel/timer.c
index dbf7a78..ebb3733 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1794,6 +1794,31 @@ void __init init_timers(void)
}
/**
+ * jsleep - sleep safely even with waitqueue interruptions
+ * @timeout: Time in jiffies to sleep for
+ */
+void jsleep(unsigned long timeout)
+{
+ while (timeout)
+ timeout = schedule_timeout_uninterruptible(timeout);
+}
+
+EXPORT_SYMBOL_GPL(jsleep);
+
+/**
+ * jsleep_interruptible - sleep waiting for signals
+ * @timeout: Time in jiffies to sleep for
+ */
+unsigned long jsleep_interruptible(unsigned long timeout)
+{
+ while (timeout && !signal_pending(current))
+ timeout = schedule_timeout_interruptible(timeout);
+ return timeout;
+}
+
+EXPORT_SYMBOL(jsleep_interruptible);
+
+/**
* msleep - sleep safely even with waitqueue interruptions
* @msecs: Time in milliseconds to sleep for
*/
@@ -1801,8 +1826,7 @@ void msleep(unsigned int msecs)
{
unsigned long timeout = msecs_to_jiffies(msecs) + 1;
- while (timeout)
- timeout = schedule_timeout_uninterruptible(timeout);
+ jsleep(timeout);
}
EXPORT_SYMBOL(msleep);
@@ -1815,9 +1839,7 @@ unsigned long msleep_interruptible(unsigned int msecs)
{
unsigned long timeout = msecs_to_jiffies(msecs) + 1;
- while (timeout && !signal_pending(current))
- timeout = schedule_timeout_interruptible(timeout);
- return jiffies_to_msecs(timeout);
+ return jiffies_to_msecs(jsleep_interruptible(timeout));
}
EXPORT_SYMBOL(msleep_interruptible);
--
1.8.1.2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
