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authorHeiner Kallweit <hkallweit1@gmail.com>2020-05-01 23:27:21 +0200
committerDavid S. Miller <davem@davemloft.net>2020-05-06 17:03:34 -0700
commitc6af13d334759c33c14b6fad4c676c6d1dbf9564 (patch)
parentipv6: Implement draft-ietf-6man-rfc4941bis (diff)
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>
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) */