[PATCH 13/17] s390: Implement arch_xor_unlock_is_negative_byte

Matthew Wilcox (Oracle)
2023-09-15T18:38:18Z

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

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
arch/s390/include/asm/bitops.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index 2de74fcd0578..c467dffa8c12 100644
--- 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>
--
2.40.1