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| author | Heiner Kallweit <hkallweit1@gmail.com> | 2020-05-02 00:27:21 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-05-07 03:03:34 +0300 |
| commit | c6af13d334759c33c14b6fad4c676c6d1dbf9564 (patch) | |
| tree | 7ec9292a89a88376a78f4ad035dc9986d1dcad7e | |
| parent | 969c54646af0d7d94a5f0f37adbbfe024e85466e (diff) | |
| download | linux-c6af13d334759c33c14b6fad4c676c6d1dbf9564.tar.xz | |
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>
| -rw-r--r-- | Documentation/timers/timers-howto.rst | 3 | ||||
| -rw-r--r-- | include/linux/delay.h | 11 |
2 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/timers/timers-howto.rst b/Documentation/timers/timers-howto.rst index 7e3167bec2b1..afb0a43b8cdf 100644 --- a/Documentation/timers/timers-howto.rst +++ b/Documentation/timers/timers-howto.rst @@ -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 diff --git a/include/linux/delay.h b/include/linux/delay.h index 8e6828094c1e..5e016a4029d9 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -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) */ |