diff options
| author | Kaleb S. KEITHLEY <kkeithle@redhat.com> | 2017-05-01 12:39:56 -0400 |
|---|---|---|
| committer | Jeff Darcy <jeff@pl.atyp.us> | 2017-05-15 14:19:01 +0000 |
| commit | 9d70343977aa870004c836a800a5cec11647b409 (patch) | |
| tree | 233c9e2b386cc17e71ca2be71b656166867c4bfb /contrib/timer-wheel/timer-wheel.c | |
| parent | 93c850dd2a513fab75408df9634ad3c970a0e859 (diff) | |
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>
Diffstat (limited to 'contrib/timer-wheel/timer-wheel.c')
| -rw-r--r-- | contrib/timer-wheel/timer-wheel.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/contrib/timer-wheel/timer-wheel.c b/contrib/timer-wheel/timer-wheel.c index 013c0f278a1..cfbd74e166f 100644 --- a/contrib/timer-wheel/timer-wheel.c +++ b/contrib/timer-wheel/timer-wheel.c @@ -1,4 +1,12 @@ /* + * linux/kernel/timer.c + * + * Kernel internal timers + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + */ +/* This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or @@ -57,9 +65,17 @@ __gf_tw_add_timer (struct tvec_base *base, struct gf_tw_timer_list *timer) list_add_tail (&timer->entry, vec); } -/* optimized find_last_bit() */ unsigned long gf_tw_find_last_bit(const unsigned long *, unsigned long); +#if defined(__GNUC__) || defined(__clang__) +static inline unsigned long gf_tw_fls (unsigned long word) +{ + return BITS_PER_LONG - __builtin_clzl(word); +} +#else +extern unsigned long gf_tw_fls (unsigned long); +#endif + static inline unsigned long apply_slack(struct tvec_base *base, struct gf_tw_timer_list *timer) { @@ -77,7 +93,7 @@ apply_slack(struct tvec_base *base, struct gf_tw_timer_list *timer) if (mask == 0) return expires; - int bit = gf_tw_find_last_bit (&mask, BITS_PER_LONG); + int bit = gf_tw_fls (mask); mask = (1UL << bit) - 1; expires_limit = expires_limit & ~(mask); |