linux-toradex.git/lib/math, branch v5.10-rc6

kernel.h: split out min()/max() et al. helpers

2020-10-16T18:11:19+00:00

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out min()/max()
et al.  helpers.

At the same time convert users in header and lib folder to use new header.
Though for time being include new header back to kernel.h to avoid
twisted indirected includes for other existing users.

Signed-off-by: Andy Shevchenko 
Signed-off-by: Andrew Morton 
Cc: "Rafael J. Wysocki" 
Cc: Steven Rostedt 
Cc: Rasmus Villemoes 
Cc: Joe Perches 
Cc: Linus Torvalds 
Link: https://lkml.kernel.org/r/20200910164152.GA1891694@smile.fi.intel.com
Signed-off-by: Linus Torvalds

lib/: replace HTTP links with HTTPS ones

2020-08-12T17:58:00+00:00

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Signed-off-by: Alexander A. Klimov 
Signed-off-by: Andrew Morton 
Acked-by: Coly Li 	[crc64.c]
Link: http://lkml.kernel.org/r/20200726112154.16510-1-grandmaster@al2klimov.de
Signed-off-by: Linus Torvalds

sched/cputime: Improve cputime_adjust()

2020-06-15T12:10:00+00:00

People report that utime and stime from /proc//stat become very
wrong when the numbers are big enough, especially if you watch these
counters incrementally.

Specifically, the current implementation of: stime*rtime/total,
results in a saw-tooth function on top of the desired line, where the
teeth grow in size the larger the values become. IOW, it has a
relative error.

The result is that, when watching incrementally as time progresses
(for large values), we'll see periods of pure stime or utime increase,
irrespective of the actual ratio we're striving for.

Replace scale_stime() with a math64.h helper: mul_u64_u64_div_u64()
that is far more accurate. This also allows architectures to override
the implementation -- for instance they can opt for the old algorithm
if this new one turns out to be too expensive for them.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200519172506.GA317395@hirez.programming.kicks-ass.net

Merge tag 'linux-kselftest-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2020-06-09T17:03:12+00:00

Pull kselftest updates from Shuah Khan:
 "This consists of:

   - Several fixes from Masami Hiramatsu to improve coverage for lib and
     sysctl tests.

   - Clean up to vdso test and a new test for getcpu() from Mark Brown.

   - Add new gen_tar selftests Makefile target generate selftest package
     running "make gen_tar" in selftests directory from Veronika
     Kabatova.

   - Other miscellaneous fixes to timens, exec, tpm2 tests"

* tag 'linux-kselftest-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  selftests/sysctl: Make sysctl test driver as a module
  selftests/sysctl: Fix to load test_sysctl module
  lib: Make test_sysctl initialized as module
  lib: Make prime number generator independently selectable
  selftests/ftrace: Return unsupported if no error_log file
  selftests/ftrace: Use printf for backslash included command
  selftests/timens: handle a case when alarm clocks are not supported
  Kernel selftests: Add check if TPM devices are supported
  selftests: vdso: Add a selftest for vDSO getcpu()
  selftests: vdso: Use a header file to prototype parse_vdso API
  selftests: vdso: Rename vdso_test to vdso_test_gettimeofday
  selftests/exec: Verify execve of non-regular files fail
  selftests: introduce gen_tar Makefile target

lib/math: avoid trailing newline hidden in pr_fmt()

2020-06-05T02:06:24+00:00

pr_xxx() functions usually have a newline at the end of the logging
message.

Here, this newline is added via the 'pr_fmt' macro.

In order to be more consistent with other files, use a more standard
convention and put these newlines back in the messages themselves and
remove it from the pr_fmt macro.

While at it, use __func__ instead of hardcoding a function name in the
last message.

Signed-off-by: Christophe JAILLET 
Signed-off-by: Andrew Morton 
Reviewed-by: Andy Shevchenko 
Cc: Mauro Carvalho Chehab 
Cc: Andrew Morton 
Cc: Greg Kroah-Hartman 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200409163234.22830-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Linus Torvalds

lib: Make prime number generator independently selectable

2020-06-02T16:25:20+00:00

Make prime number generator independently selectable from
kconfig. This allows us to enable CONFIG_PRIME_NUMBERS=m
and run the tools/testing/selftests/lib/prime_numbers.sh
without other DRM selftest modules.

Signed-off-by: Masami Hiramatsu 
Reviewed-by: Kees Cook 
Reviewed-by: Luis Chamberlain 
Signed-off-by: Shuah Khan

lib/math/rational.c: fix possible incorrect result from rational fractions helper

2019-12-05T03:44:13+00:00

In some cases the previous algorithm would not return the closest
approximation.  This would happen when a semi-convergent was the
closest, as the previous algorithm would only consider convergents.

As an example, consider an initial value of 5/4, and trying to find the
closest approximation with a maximum of 4 for numerator and denominator.
The previous algorithm would return 1/1 as the closest approximation,
while this version will return the correct answer of 4/3.

To do this, the main loop performs effectively the same operations as it
did before.  It must now keep track of the last three approximations,
n2/d2 ..  n0/d0, while before it only needed the last two.

If an exact answer is not found, the algorithm will now calculate the
best semi-convergent term, t, which is a single expression with two
divisions:

    min((max_numerator - n0) / n1, (max_denominator - d0) / d1)

This will be used if it is better than previous convergent.  The test
for this is generally a simple comparison, 2*t > a.  But in an edge
case, where the convergent's final term is even and the best allowable
semi-convergent has a final term of exactly half the convergent's final
term, the more complex comparison (d0*dp > d1*d) is used.

I also wrote some comments explaining the code.  While one still needs
to look up the math elsewhere, they should help a lot to follow how the
code relates to that math.

This routine is used in two places in the video4linux code, but in those
cases it is only used to reduce a fraction to lowest terms, which the
existing code will do correctly.  This could be done more efficiently
with a different library routine but it would still be the Euclidean
alogrithm at its heart.  So no change.

The remain users are places where a fractional PLL divider is
programmed.  What would happen is something asked for a clock of X MHz
but instead gets Y MHz, where Y is close to X but not exactly due to the
hardware limitations.  After this change they might, in some cases, get
Y' MHz, where Y' is a little closer to X then Y was.

Users like this are: Three UARTs, in 8250_mid, 8250_lpss, and imx.  One
GPU in vp4_hdmi.  And three clock drivers, clk-cdce706, clk-si5351, and
clk-fractional-divider.  The last is a generic clock driver and so would
have more users referenced via device tree entries.

I think there's a bug in that one, it's limiting an N bit field that is
offset-by-1 to the range 0 ..  (1<
Cc: Oskar Schirmer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21T08:50:46+00:00

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

treewide: Add SPDX license identifier for more missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have MODULE_LICENCE("GPL*") inside which was used in the initial
   scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman