[PATCH v13 02/13] cpumask: Introduce cpumask_intersects_and
From: Shrikanth Hegde <sshegde@linux.ibm.com>
Date: 2026-09-09 13:57:16
Also in:
lkml, virtualization
Subsystem:
bitmap api, library code, the rest · Maintainers:
Yury Norov, Andrew Morton, Linus Torvalds
Introduce bitmap_intersects_and() to determine whether the intersection of three bitmaps is non-empty. Unlike cpumask_first_and_and(), this returns immediately when an intersecting word is found and does not calculate the first matching bit. Add cpumask_intersects_and() as the corresponding cpumask wrapper. A subsequent patch uses the helper to determine whether a task has a CPU that is present in its affinity mask, the preferred CPU mask, and task possible CPU mask. Suggested-by: Yury Norov <yury.norov@gmail.com> Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> --- include/linux/bitmap.h | 14 ++++++++++++++ include/linux/cpumask.h | 18 ++++++++++++++++++ lib/bitmap.c | 17 +++++++++++++++++ 3 files changed, 49 insertions(+)
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 7df1573a409c..adafbcf2016b 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h@@ -52,6 +52,7 @@ struct device; * bitmap_complement(dst, src, nbits) *dst = ~(*src) * bitmap_equal(src1, src2, nbits) Are *src1 and *src2 equal? * bitmap_intersects(src1, src2, nbits) Do *src1 and *src2 overlap? + * bitmap_intersects_and(src1, src2, src3, nbits) Do *src1, *src2 and *src3 overlap? * bitmap_subset(src1, src2, nbits) Is *src1 a subset of *src2? * bitmap_empty(src, nbits) Are all bits zero in *src? * bitmap_full(src, nbits) Are all bits set in *src?
@@ -181,6 +182,9 @@ void __bitmap_replace(unsigned long *dst, const unsigned long *mask, unsigned int nbits); bool __bitmap_intersects(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int nbits); +bool __bitmap_intersects_and(const unsigned long *bitmap1, + const unsigned long *bitmap2, + const unsigned long *bitmap3, unsigned int nbits); bool __bitmap_subset(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int nbits); unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
@@ -445,6 +449,16 @@ bool bitmap_intersects(const unsigned long *src1, const unsigned long *src2, uns return __bitmap_intersects(src1, src2, nbits); } +static __always_inline +bool bitmap_intersects_and(const unsigned long *src1, const unsigned long *src2, + const unsigned long *src3, unsigned int nbits) +{ + if (small_const_nbits(nbits)) + return ((*src1 & *src2 & *src3) & BITMAP_LAST_WORD_MASK(nbits)) != 0; + else + return __bitmap_intersects_and(src1, src2, src3, nbits); +} + static __always_inline bool bitmap_subset(const unsigned long *src1, const unsigned long *src2, unsigned int nbits) {
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 4c8bb6953107..7c8f16797f94 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h@@ -824,6 +824,24 @@ bool cpumask_intersects(const struct cpumask *src1p, const struct cpumask *src2p small_cpumask_bits); } +/** + * cpumask_intersects_and - (*src1p & *src2p & *src3p) != 0 + * @src1p: the first input + * @src2p: the second input + * @src3p: the third input + * + * Return: true if AND of the three cpumasks is non-empty, + * otherwise false + */ +static __always_inline +bool cpumask_intersects_and(const struct cpumask *src1p, + const struct cpumask *src2p, + const struct cpumask *src3p) +{ + return bitmap_intersects_and(cpumask_bits(src1p), cpumask_bits(src2p), + cpumask_bits(src3p), small_cpumask_bits); +} + /** * cpumask_subset - (*src1p & ~*src2p) == 0 * @src1p: the first input
diff --git a/lib/bitmap.c b/lib/bitmap.c
index ed685127a107..d1cb8a507c60 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c@@ -308,6 +308,23 @@ bool __bitmap_intersects(const unsigned long *bitmap1, } EXPORT_SYMBOL(__bitmap_intersects); +bool __bitmap_intersects_and(const unsigned long *bitmap1, + const unsigned long *bitmap2, + const unsigned long *bitmap3, unsigned int bits) +{ + unsigned int k, lim = bits / BITS_PER_LONG; + + for (k = 0; k < lim; ++k) + if (bitmap1[k] & bitmap2[k] & bitmap3[k]) + return true; + + if (bits % BITS_PER_LONG) + if ((bitmap1[k] & bitmap2[k] & bitmap3[k]) & BITMAP_LAST_WORD_MASK(bits)) + return true; + return false; +} +EXPORT_SYMBOL(__bitmap_intersects_and); + bool __bitmap_subset(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int bits) {
--
2.52.0