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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2017-03-24 17:00:45 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-04-12 08:43:33 +0200
commitb13de4b7adeb7a5e37a5aa78d5a4926c3cd4e131 (patch)
tree472c2bdb751e5529b403dd297b76ae08f25a7d9a /arch/s390/lib
parent02c503ff237cdcd8e012a122a638295550db10a5 (diff)
s390/spinlock: remove compare and delay instruction
The CAD instruction never worked quite as expected for the spinlock code. It has been disabled by default with git commit 61b0b01686d48220, if the "cad" kernel parameter is specified it is enabled for both user space and the spinlock code. Leave the option to enable the instruction for user space but remove it from the spinlock code. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib')
-rw-r--r--arch/s390/lib/spinlock.c33
1 files changed, 5 insertions, 28 deletions
diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
index 3f4d0c69bbfe..ffb15bd4c593 100644
--- a/arch/s390/lib/spinlock.c
+++ b/arch/s390/lib/spinlock.c
@@ -17,7 +17,7 @@ int spin_retry = -1;
static int __init spin_retry_init(void)
{
if (spin_retry < 0)
- spin_retry = MACHINE_HAS_CAD ? 10 : 1000;
+ spin_retry = 1000;
return 0;
}
early_initcall(spin_retry_init);
@@ -32,11 +32,6 @@ static int __init spin_retry_setup(char *str)
}
__setup("spin_retry=", spin_retry_setup);
-static inline void compare_and_delay(int *lock, int old)
-{
- asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock));
-}
-
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int cpu = SPINLOCK_LOCKVAL;
@@ -60,8 +55,6 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
/* Loop for a while on the lock value. */
count = spin_retry;
do {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0);
if (!owner)
@@ -105,8 +98,6 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
/* Loop for a while on the lock value. */
count = spin_retry;
do {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
owner = ACCESS_ONCE(lp->lock);
} while (owner && count-- > 0);
if (!owner)
@@ -135,8 +126,7 @@ int arch_spin_trylock_retry(arch_spinlock_t *lp)
if (!owner) {
if (__atomic_cmpxchg_bool(&lp->lock, 0, cpu))
return 1;
- } else if (MACHINE_HAS_CAD)
- compare_and_delay(&lp->lock, owner);
+ }
}
return 0;
}
@@ -159,11 +149,8 @@ void _raw_read_lock_wait(arch_rwlock_t *rw)
}
old = ACCESS_ONCE(rw->lock);
owner = ACCESS_ONCE(rw->owner);
- if (old < 0) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old < 0)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return;
}
@@ -177,11 +164,8 @@ int _raw_read_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
- if (old < 0) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old < 0)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, old, old + 1))
return 1;
}
@@ -212,8 +196,6 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, int prev)
}
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
@@ -242,8 +224,6 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
smp_mb();
if ((old & 0x7fffffff) == 0 && prev >= 0)
break;
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
@@ -257,11 +237,8 @@ int _raw_write_trylock_retry(arch_rwlock_t *rw)
while (count-- > 0) {
old = ACCESS_ONCE(rw->lock);
- if (old) {
- if (MACHINE_HAS_CAD)
- compare_and_delay(&rw->lock, old);
+ if (old)
continue;
- }
if (__atomic_cmpxchg_bool(&rw->lock, 0, 0x80000000))
return 1;
}

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