On Wed, Sep 09, 2026 at 07:26:06PM +0530, Shrikanth Hegde wrote: > 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 <[email protected]> > Signed-off-by: Shrikanth Hegde <[email protected]>
Reviwed-by: Yury Norov <[email protected]> > --- > 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
