linux.git/kernel/time/timecounter.c, branch v6.18.21

time/timecounter: Fix the lie that struct cyclecounter is const

2025-07-01T13:38:25+00:00

In both the read callback for struct cyclecounter, and in struct
timecounter, struct cyclecounter is declared as a const pointer.

Unfortunatly, a number of users of this pointer treat it as a non-const
pointer as it is burried in a larger structure that is heavily modified by
the callback function when accessed.  This lie had been hidden by the fact
that container_of() "casts away" a const attribute of a pointer without any
compiler warning happening at all.

Fix this all up by removing the const attribute in the needed places so
that everyone can see that the structure really isn't const, but can,
and is, modified by the users of it.

Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/2025070124-backyard-hurt-783a@gregkh

time/timecounter: Mark 1st argument of timecounter_cyc2time() as const

2021-04-16T19:03:50+00:00

The timecounter is not modified in this function. Mark it as const.

Signed-off-by: Marc Kleine-Budde 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20210303103544.994855-1-mkl@pengutronix.de

time: Remove license boilerplate

2018-11-23T10:51:21+00:00

The SPDX identifier defines the license of the files already. No need for
the boilerplates.

Signed-off-by: Thomas Gleixner 
Acked-by: Kees Cook 
Acked-by: Ingo Molnar 
Acked-by: John Stultz 
Acked-by: Corey Minyard 
Acked-by: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Peter Anvin 
Cc: Russell King 
Cc: Richard Cochran 
Cc: Nicolas Pitre 
Cc: David Riley 
Cc: Colin Cross 
Cc: Mark Brown 
Cc: Paul E. McKenney 
Link: https://lkml.kernel.org/r/20181031182253.132458951@linutronix.de

time: Add SPDX license identifiers

2018-11-23T10:51:20+00:00

Update the time(r) core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of the
full boiler plate text.

This work is based on a script and data from Philippe Ombredanne, Kate
Stewart and myself. The data has been created with two independent license
scanners and manual inspection.

The following files do not contain any direct license information and have
been omitted from the big initial SPDX changes:

  timeconst.bc: The .bc files were not touched
  time.c, timer.c, timekeeping.c: Licence was deduced from EXPORT_SYMBOL_GPL

As those files do not contain direct license references they fall under the
project license, i.e. GPL V2 only.

Signed-off-by: Thomas Gleixner 
Acked-by: Kees Cook 
Acked-by: Ingo Molnar 
Acked-by: John Stultz 
Acked-by: Corey Minyard 
Cc: Peter Zijlstra 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Russell King 
Cc: Richard Cochran 
Cc: Nicolas Pitre 
Cc: David Riley 
Cc: Colin Cross 
Cc: Mark Brown 
Cc: H. Peter Anvin 
Cc: Paul E. McKenney 
Link: https://lkml.kernel.org/r/20181031182252.879109557@linutronix.de

time: Remove useless filenames in top level comments

2018-11-23T10:51:20+00:00

Remove the pointless filenames in the top level comments. They have no
value at all and just occupy space. While at it tidy up some of the
comments and remove a stale one.

Signed-off-by: Thomas Gleixner 
Acked-by: Nicolas Pitre 
Acked-by: Kees Cook 
Acked-by: Ingo Molnar 
Acked-by: John Stultz 
Acked-by: Corey Minyard 
Cc: Peter Zijlstra 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Peter Anvin 
Cc: Russell King 
Cc: Richard Cochran 
Cc: "Paul E. McKenney" 
Cc: David Riley 
Cc: Colin Cross 
Cc: Mark Brown 
Link: https://lkml.kernel.org/r/20181031182252.794898238@linutronix.de

clocksource: Use a plain u64 instead of cycle_t

2016-12-25T10:04:12+00:00

There is no point in having an extra type for extra confusion. u64 is
unambiguous.

Conversion was done with the following coccinelle script:

@rem@
@@
-typedef u64 cycle_t;

@fix@
typedef cycle_t;
@@
-cycle_t
+u64

Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: John Stultz

timecounter: keep track of accumulated fractional nanoseconds

2014-12-30T23:29:27+00:00

The current timecounter implementation will drop a variable amount
of resolution, depending on the magnitude of the time delta. In
other words, reading the clock too often or too close to a time
stamp conversion will introduce errors into the time values. This
patch fixes the issue by introducing a fractional nanosecond field
that accumulates the low order bits.

Reported-by: Janusz Użycki 
Signed-off-by: Richard Cochran 
Signed-off-by: David S. Miller

time: move the timecounter/cyclecounter code into its own file.

2014-12-30T23:29:25+00:00

The timecounter code has almost nothing to do with the clocksource
code. Let it live in its own file. This will help isolate the
timecounter users from the clocksource users in the source tree.

Signed-off-by: Richard Cochran 
Acked-by: Jeff Kirsher 
Signed-off-by: David S. Miller