contrib/timerwheel: bad 32-bit, use builtin fls(), fix copyright

It's bad form to remove other people's copyright and license when you
copy their source for your own use.

Defining BITS_PER_LONG as 64 is incorrect on 32-bit platforms.

The mismatch between the unsigned long of the timer and the int
param to fls() means on 64-bit platforms that any bits set in the
high 32-bits of the the timer are lost/ignored.

gf_tw_find_last_bit() is meant to find the last bit in an array of
longs. It's overkill for gluster's timerwheel  where we only ever pass
a single long; replacing it with a direct call to fls() which is
renamed to gf_tw_fls()

The timer routines are slightly modified from the kernel timer
functions that first appeared circa 2.6.x in .../kernel/timer.c
AFAICT.

find_last_bit() comes from the (linux) kernel (.../lib/find_bit.c
in 4.x kernels, .../lib/find_last_bit.c in 3.x kernels) but as noted
above, it is removed with this patch.

__fls() comes from the linux kernel (.../include/asm-generic/
bitops/{__fls.h,builtin-__fls.h}

Restoring/updating the copyright and license to the version from
the 4.x kernel find_bit.c. (timer.c does not have a license, __fls.h
and builtin-__fls.h do not have a copyright or license, but the whole
kernel is licensed under GPLv2 anyway.)

Change-Id: I2d2defccf1ccc74f55d99e94212747a36a1dff35
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>
Reviewed-on: https://review.gluster.org/17146
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>

0 files changed, 0 insertions, 0 deletions