Commit d28d86a0 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/mm: make use of atomic_fetch_xor() 



Make use of atomic_fetch_xor() instead of an atomic_cmpxchg() loop to
implement atomic_xor_bits() (aka atomic_xor_return()). This makes the C
code more readable and in addition generates better code, since for z196
and newer a single lax instruction is generated instead of a cmpxchg()
loop.

Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 038c5bed

arch/s390/mm/pgalloc.c

+1 −7
Original line number Diff line number Diff line
@@ -133,13 +133,7 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 


static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)

{

	unsigned int old, new;



	do {

		old = atomic_read(v);

		new = old ^ bits;

	} while (atomic_cmpxchg(v, old, new) != old);

	return new;

	return atomic_fetch_xor(bits, v) ^ bits;

}



#ifdef CONFIG_PGSTE