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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 /include | |
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 'include')
-rw-r--r-- | include/linux/bitmap.h | 23 | ||||
-rw-r--r-- | include/linux/cpumask.h | 41 |
2 files changed, 55 insertions, 9 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index f58e97446abc..90528f12bdfa 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -120,6 +120,10 @@ extern int __bitmap_empty(const unsigned long *bitmap, unsigned int nbits); extern int __bitmap_full(const unsigned long *bitmap, unsigned int nbits); extern int __bitmap_equal(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int nbits); +extern bool __pure __bitmap_or_equal(const unsigned long *src1, + const unsigned long *src2, + const unsigned long *src3, + unsigned int nbits); extern void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int nbits); extern void __bitmap_shift_right(unsigned long *dst, const unsigned long *src, @@ -321,6 +325,25 @@ static inline int bitmap_equal(const unsigned long *src1, return __bitmap_equal(src1, src2, nbits); } +/** + * bitmap_or_equal - Check whether the or of two bitnaps is equal to a third + * @src1: Pointer to bitmap 1 + * @src2: Pointer to bitmap 2 will be or'ed with bitmap 1 + * @src3: Pointer to bitmap 3. Compare to the result of *@src1 | *@src2 + * + * Returns: True if (*@src1 | *@src2) == *@src3, false otherwise + */ +static inline bool bitmap_or_equal(const unsigned long *src1, + const unsigned long *src2, + const unsigned long *src3, + unsigned int nbits) +{ + if (!small_const_nbits(nbits)) + return __bitmap_or_equal(src1, src2, src3, nbits); + + return !(((*src1 | *src2) ^ *src3) & BITMAP_LAST_WORD_MASK(nbits)); +} + static inline int bitmap_intersects(const unsigned long *src1, const unsigned long *src2, unsigned int nbits) { diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 21755471b1c3..b5a5a1ed9efd 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -10,6 +10,7 @@ #include <linux/kernel.h> #include <linux/threads.h> #include <linux/bitmap.h> +#include <linux/atomic.h> #include <linux/bug.h> /* Don't assign or return these: may not be this big! */ @@ -95,8 +96,21 @@ extern struct cpumask __cpu_active_mask; #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) +extern atomic_t __num_online_cpus; + #if NR_CPUS > 1 -#define num_online_cpus() cpumask_weight(cpu_online_mask) +/** + * num_online_cpus() - Read the number of online CPUs + * + * Despite the fact that __num_online_cpus is of type atomic_t, this + * interface gives only a momentary snapshot and is not protected against + * concurrent CPU hotplug operations unless invoked from a cpuhp_lock held + * region. + */ +static inline unsigned int num_online_cpus(void) +{ + return atomic_read(&__num_online_cpus); +} #define num_possible_cpus() cpumask_weight(cpu_possible_mask) #define num_present_cpus() cpumask_weight(cpu_present_mask) #define num_active_cpus() cpumask_weight(cpu_active_mask) @@ -115,6 +129,8 @@ extern struct cpumask __cpu_active_mask; #define cpu_active(cpu) ((cpu) == 0) #endif +extern cpumask_t cpus_booted_once_mask; + static inline void cpu_max_bits_warn(unsigned int cpu, unsigned int bits) { #ifdef CONFIG_DEBUG_PER_CPU_MAPS @@ -474,6 +490,20 @@ static inline bool cpumask_equal(const struct cpumask *src1p, } /** + * cpumask_or_equal - *src1p | *src2p == *src3p + * @src1p: the first input + * @src2p: the second input + * @src3p: the third input + */ +static inline bool cpumask_or_equal(const struct cpumask *src1p, + const struct cpumask *src2p, + const struct cpumask *src3p) +{ + return bitmap_or_equal(cpumask_bits(src1p), cpumask_bits(src2p), + cpumask_bits(src3p), nr_cpumask_bits); +} + +/** * cpumask_intersects - (*src1p & *src2p) != 0 * @src1p: the first input * @src2p: the second input @@ -805,14 +835,7 @@ set_cpu_present(unsigned int cpu, bool present) cpumask_clear_cpu(cpu, &__cpu_present_mask); } -static inline void -set_cpu_online(unsigned int cpu, bool online) -{ - if (online) - cpumask_set_cpu(cpu, &__cpu_online_mask); - else - cpumask_clear_cpu(cpu, &__cpu_online_mask); -} +void set_cpu_online(unsigned int cpu, bool online); static inline void set_cpu_active(unsigned int cpu, bool active) |