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Wed, 07 Sep 2022 09:27:13 -0700 (PDT) X-Google-Smtp-Source: AA6agR6VLl5PWL5bBBvM1hJQeEpH4ZGE9QTiQIIhTWlhIiA3jVFHC2480Z1kdNgMXLVbblZSnLVaig== X-Received: by 2002:a5d:6c62:0:b0:222:c8cd:26f with SMTP id r2-20020a5d6c62000000b00222c8cd026fmr2660035wrz.393.1662568033539; Wed, 07 Sep 2022 09:27:13 -0700 (PDT) Received: from vschneid.remote.csb ([185.11.37.247]) by smtp.gmail.com with ESMTPSA id z14-20020a5d4c8e000000b0021e4829d359sm18030720wrs.39.2022.09.07.09.27.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Sep 2022 09:27:13 -0700 (PDT) From: Valentin Schneider To: Yury Norov , Linus Torvalds , linux-kernel@vger.kernel.org Cc: Yury Norov , Alexey Klimov , Andy Shevchenko , Andy Whitcroft , Catalin Marinas , David Laight , Dennis Zhou , Guenter Roeck , Kees Cook , Rasmus Villemoes , Russell King Subject: Re: [PATCH v3 2/4] lib/find_bit: create find_first_zero_bit_le() In-Reply-To: <20220827175807.4017673-3-yury.norov@gmail.com> References: <20220827175807.4017673-1-yury.norov@gmail.com> <20220827175807.4017673-3-yury.norov@gmail.com> Date: Wed, 07 Sep 2022 17:27:12 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/08/22 10:58, Yury Norov wrote: > find_first_zero_bit_le() is an alias to find_next_zero_bit_le(), > despite that 'next' is known to be slower than 'first' version. > > Now that we have common FIND_FIRST_BIT() macro helper, it's trivial > to implement find_first_zero_bit_le() as a real function. > > Signed-off-by: Yury Norov Declaration ordering nit below, otherwise: Reviewed-by: Valentin Schneider > --- > include/linux/find.h | 23 ++++++++++++++++++----- > lib/find_bit.c | 14 ++++++++++++++ > 2 files changed, 32 insertions(+), 5 deletions(-) > > diff --git a/include/linux/find.h b/include/linux/find.h > index 424ef67d4a42..a1861d0ba533 100644 > --- a/include/linux/find.h > +++ b/include/linux/find.h > @@ -17,6 +17,10 @@ extern unsigned long _find_first_and_bit(const unsigned long *addr1, > extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size); > extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size); > > +#ifdef __BIG_ENDIAN > +unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size); > +#endif > + > #ifndef find_next_bit > /** > * find_next_bit - find the next set bit in a memory region > @@ -251,6 +255,20 @@ unsigned long find_next_zero_bit_le(const void *addr, unsigned > } > #endif > > +#ifndef find_first_zero_bit_le > +static inline > +unsigned long find_first_zero_bit_le(const unsigned long *addr, unsigned long size) > +{ > + if (small_const_nbits(size)) { > + unsigned long val = swab(*addr) | ~GENMASK(size - 1, 0); > + > + return val == ~0UL ? size : ffz(val); > + } > + > + return _find_first_zero_bit_le(addr, size); > +} > +#endif > + Nit: this should be placed after the declaration of find_next_bit_le() to match the __LITTLE_ENDIAN declaration order above. > #ifndef find_next_bit_le > static inline > unsigned long find_next_bit_le(const void *addr, unsigned > @@ -270,11 +288,6 @@ unsigned long find_next_bit_le(const void *addr, unsigned > } > #endif > > -#ifndef find_first_zero_bit_le > -#define find_first_zero_bit_le(addr, size) \ > - find_next_zero_bit_le((addr), (size), 0) > -#endif > - > #else > #error "Please fix " > #endif > diff --git a/lib/find_bit.c b/lib/find_bit.c > index 894b656f6836..f4d9b9684811 100644 > --- a/lib/find_bit.c > +++ b/lib/find_bit.c > @@ -160,3 +160,17 @@ unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr, > return offset; > } > EXPORT_SYMBOL(find_next_clump8); > + > +#ifdef __BIG_ENDIAN > +#ifndef find_first_zero_bit_le > +/* > + * Find the first cleared bit in an LE memory region. > + */ > +unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size) > +{ > + return FIND_FIRST_BIT(~addr[idx], swab, size); > +} > +EXPORT_SYMBOL(_find_first_zero_bit_le); > +#endif > + > +#endif /* __BIG_ENDIAN */ > -- > 2.34.1