s390: implement arch_xor_unlock_is_negative_byte

Inspired by the s390 arch_test_and_clear_bit(), this will surely be more
efficient than the generic one defined in filemap.c.

Link: https://lkml.kernel.org/r/20231004165317.1061855-14-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>

diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index 2de74fcd0578f42c25d178f4f3ef1dbbaa30158c..c467dffa8c12a5714d5aad1986bbf5cab801bbf0 100644 (file)
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -201,6 +201,16 @@ static inline void arch___clear_bit_unlock(unsigned long nr,
        arch___clear_bit(nr, ptr);
 }
 
+static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
+               volatile unsigned long *ptr)
+{
+       unsigned long old;
+
+       old = __atomic64_xor_barrier(mask, (long *)ptr);
+       return old & BIT(7);
+}
+#define arch_xor_unlock_is_negative_byte arch_xor_unlock_is_negative_byte
+
 #include <asm-generic/bitops/instrumented-atomic.h>
 #include <asm-generic/bitops/instrumented-non-atomic.h>
 #include <asm-generic/bitops/instrumented-lock.h>