Commit c6af13d3 authored May 01, 2020 by Heiner Kallweit Committed by David S. Miller May 06, 2020

timer: add fsleep for flexible sleeping



Sleeping for a certain amount of time requires use of different
functions, depending on the time period.
Documentation/timers/timers-howto.rst explains when to use which
function, and also checkpatch checks for some potentially
problematic cases.

So let's create a helper that automatically chooses the appropriate
sleep function -> fsleep(), for flexible sleeping

If the delay is a constant, then the compiler should be able to ensure
that the new helper doesn't create overhead. If the delay is not
constant, then the new helper can save some code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 969c5464

Documentation/timers/timers-howto.rst

+3 −0

Original line number	Diff line number	Diff line
		@@ -110,3 +110,6 @@ 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.

		FLEXIBLE SLEEPING (any delay, uninterruptible)
		* Use fsleep

include/linux/delay.h

+11 −0

Original line number	Diff line number	Diff line
		@@ -65,4 +65,15 @@ static inline void ssleep(unsigned int seconds)
		msleep(seconds * 1000);
		}

		/* see Documentation/timers/timers-howto.rst for the thresholds */
		static inline void fsleep(unsigned long usecs)
		{
		if (usecs <= 10)
		udelay(usecs);
		else if (usecs <= 20000)
		usleep_range(usecs, 2 * usecs);
		else
		msleep(DIV_ROUND_UP(usecs, 1000));
		}

		#endif /* defined(_LINUX_DELAY_H) */

Admin message