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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-17 20:32:05 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-17 20:32:05 +0300 |
commit | 3cd0462230d806077c709e44af8733795eaa712c (patch) | |
tree | 1b9cfe66a3d8adf91d4907b01a0b86807d2d669b /lib | |
parent | 16208cd6c36ac558c2c09042feb2b61e1e58f78a (diff) | |
parent | 0c09ab96fc820109d63097a2adcbbd20836b655f (diff) | |
download | linux-3cd0462230d806077c709e44af8733795eaa712c.tar.xz |
Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull CPU hotplug updates from Thomas Gleixner:
"A small update for the SMP hotplug code code:
- Track "booted once" CPUs in a cpumask so the x86 APIC code has an
easy way to decide whether broadcast IPIs are safe to use or not.
- Implement a cpumask_or_equal() helper for the IPI broadcast
evaluation.
The above two changes have been also pulled into the x86/apic
branch for implementing the conditional IPI broadcast feature.
- Cache the number of online CPUs instead of reevaluating it over and
over. num_online_cpus() is an unreliable snapshot anyway except
when it is used outside a cpu hotplug locked region. The cached
access is not changing this, but it's definitely faster than
calculating the bitmap wheight especially in hot paths"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Cache number of online CPUs
cpumask: Implement cpumask_or_equal()
smp/hotplug: Track booted once CPUs in a cpumask
Diffstat (limited to 'lib')
-rw-r--r-- | lib/bitmap.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/bitmap.c b/lib/bitmap.c index bbe2589e8497..f9e834841e94 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -59,6 +59,26 @@ int __bitmap_equal(const unsigned long *bitmap1, } EXPORT_SYMBOL(__bitmap_equal); +bool __bitmap_or_equal(const unsigned long *bitmap1, + const unsigned long *bitmap2, + const unsigned long *bitmap3, + unsigned int bits) +{ + unsigned int k, lim = bits / BITS_PER_LONG; + unsigned long tmp; + + for (k = 0; k < lim; ++k) { + if ((bitmap1[k] | bitmap2[k]) != bitmap3[k]) + return false; + } + + if (!(bits % BITS_PER_LONG)) + return true; + + tmp = (bitmap1[k] | bitmap2[k]) ^ bitmap3[k]; + return (tmp & BITMAP_LAST_WORD_MASK(bits)) == 0; +} + void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits) { unsigned int k, lim = BITS_TO_LONGS(bits); |