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s390/mm: make use of atomic_fetch_xor()

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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: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2023-03-17 14:51:41 +01:00
parent 038c5bedbc
commit d28d86a07d
1 changed files with 1 additions and 7 deletions
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8
arch/s390/mm/pgalloc.c
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@ -133,13 +133,7 @@ err_p4d:
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