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mips: implement xor_unlock_is_negative_byte 

Inspired by the mips test_and_change_bit(), this will surely be more
efficient than the generic one defined in filemap.c

Link: https://lkml.kernel.org/r/20231004165317.1061855-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-10-04 17:53:10 +01:00 committed by Andrew Morton
parent ea845e3173
commit 8da36b26e3
2 changed files with 39 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
arch/mips/include/asm/bitops.h
View File

@ -73,7 +73,8 @@ int __mips_test_and_clear_bit(unsigned long nr,
volatile unsigned long *addr);
int __mips_test_and_change_bit(unsigned long nr,
volatile unsigned long *addr);
bool __mips_xor_is_negative_byte(unsigned long mask,
volatile unsigned long *addr);
/*
* set_bit - Atomically set a bit in memory
@ -279,6 +280,29 @@ static inline int test_and_change_bit(unsigned long nr,
return res;
}
static inline bool xor_unlock_is_negative_byte(unsigned long mask,
volatile unsigned long *p)
{
unsigned long orig;
bool res;
smp_mb__before_atomic();
if (!kernel_uses_llsc) {
res = __mips_xor_is_negative_byte(mask, p);
} else {
orig = __test_bit_op(*p, "%0",
"xor\t%1, %0, %3",
"ir"(mask));
res = (orig & BIT(7)) != 0;
}
smp_llsc_mb();
return res;
}
#define xor_unlock_is_negative_byte xor_unlock_is_negative_byte
#undef __bit_op
#undef __test_bit_op

14
arch/mips/lib/bitops.c
View File

@ -146,3 +146,17 @@ int __mips_test_and_change_bit(unsigned long nr, volatile unsigned long *addr)
return res;
}
EXPORT_SYMBOL(__mips_test_and_change_bit);
bool __mips_xor_is_negative_byte(unsigned long mask,
volatile unsigned long *addr)
{
unsigned long flags;
unsigned long data;
raw_local_irq_save(flags);
data = *addr;
*addr = data ^ mask;
raw_local_irq_restore(flags);
return (data & BIT(7)) != 0;
}