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kernel-fxtec-pro1x/arch/s390/include/asm/rwsem.h
Heiko Carstens a53c8fab3f s390/comments: unify copyright messages and remove file names 
Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2012-07-20 11:15:04 +02:00

318 lines
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#ifndef _S390_RWSEM_H
#define _S390_RWSEM_H
/*
* S390 version
* Copyright IBM Corp. 2002
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
*/
/*
*
* The MSW of the count is the negated number of active writers and waiting
* lockers, and the LSW is the total number of active locks
*
* The lock count is initialized to 0 (no active and no waiting lockers).
*
* When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an
* uncontended lock. This can be determined because XADD returns the old value.
* Readers increment by 1 and see a positive value when uncontended, negative
* if there are writers (and maybe) readers waiting (in which case it goes to
* sleep).
*
* The value of WAITING_BIAS supports up to 32766 waiting processes. This can
* be extended to 65534 by manually checking the whole MSW rather than relying
* on the S flag.
*
* The value of ACTIVE_BIAS supports up to 65535 active processes.
*
* This should be totally fair - if anything is waiting, a process that wants a
* lock will go to the back of the queue. When the currently active lock is
* released, if there's a writer at the front of the queue, then that and only
* that will be woken up; if there's a bunch of consequtive readers at the
* front, then they'll all be woken up, but no other readers will be.
*/
#ifndef _LINUX_RWSEM_H
#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
#endif
#ifndef CONFIG_64BIT
#define RWSEM_UNLOCKED_VALUE 0x00000000
#define RWSEM_ACTIVE_BIAS 0x00000001
#define RWSEM_ACTIVE_MASK 0x0000ffff
#define RWSEM_WAITING_BIAS (-0x00010000)
#else /* CONFIG_64BIT */
#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L
#define RWSEM_ACTIVE_BIAS 0x0000000000000001L
#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL
#define RWSEM_WAITING_BIAS (-0x0000000100000000L)
#endif /* CONFIG_64BIT */
#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
/*
* lock for reading
*/
static inline void __down_read(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" ahi %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" aghi %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "i" (RWSEM_ACTIVE_READ_BIAS)
: "cc", "memory");
if (old < 0)
rwsem_down_read_failed(sem);
}
/*
* trylock for reading -- returns 1 if successful, 0 if contention
*/
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: ltr %1,%0\n"
" jm 1f\n"
" ahi %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b\n"
"1:"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: ltgr %1,%0\n"
" jm 1f\n"
" aghi %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b\n"
"1:"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "i" (RWSEM_ACTIVE_READ_BIAS)
: "cc", "memory");
return old >= 0 ? 1 : 0;
}
/*
* lock for writing
*/
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
signed long old, new, tmp;
tmp = RWSEM_ACTIVE_WRITE_BIAS;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" a %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" ag %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "m" (tmp)
: "cc", "memory");
if (old != 0)
rwsem_down_write_failed(sem);
}
static inline void __down_write(struct rw_semaphore *sem)
{
__down_write_nested(sem, 0);
}
/*
* trylock for writing -- returns 1 if successful, 0 if contention
*/
static inline int __down_write_trylock(struct rw_semaphore *sem)
{
signed long old;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%1\n"
"0: ltr %0,%0\n"
" jnz 1f\n"
" cs %0,%3,%1\n"
" jl 0b\n"
#else /* CONFIG_64BIT */
" lg %0,%1\n"
"0: ltgr %0,%0\n"
" jnz 1f\n"
" csg %0,%3,%1\n"
" jl 0b\n"
#endif /* CONFIG_64BIT */
"1:"
: "=&d" (old), "=Q" (sem->count)
: "Q" (sem->count), "d" (RWSEM_ACTIVE_WRITE_BIAS)
: "cc", "memory");
return (old == RWSEM_UNLOCKED_VALUE) ? 1 : 0;
}
/*
* unlock after reading
*/
static inline void __up_read(struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" ahi %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" aghi %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "i" (-RWSEM_ACTIVE_READ_BIAS)
: "cc", "memory");
if (new < 0)
if ((new & RWSEM_ACTIVE_MASK) == 0)
rwsem_wake(sem);
}
/*
* unlock after writing
*/
static inline void __up_write(struct rw_semaphore *sem)
{
signed long old, new, tmp;
tmp = -RWSEM_ACTIVE_WRITE_BIAS;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" a %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" ag %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "m" (tmp)
: "cc", "memory");
if (new < 0)
if ((new & RWSEM_ACTIVE_MASK) == 0)
rwsem_wake(sem);
}
/*
* downgrade write lock to read lock
*/
static inline void __downgrade_write(struct rw_semaphore *sem)
{
signed long old, new, tmp;
tmp = -RWSEM_WAITING_BIAS;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" a %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" ag %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "m" (tmp)
: "cc", "memory");
if (new > 1)
rwsem_downgrade_wake(sem);
}
/*
* implement atomic add functionality
*/
static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" ar %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" agr %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "d" (delta)
: "cc", "memory");
}
/*
* implement exchange and add functionality
*/
static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
signed long old, new;
asm volatile(
#ifndef CONFIG_64BIT
" l %0,%2\n"
"0: lr %1,%0\n"
" ar %1,%4\n"
" cs %0,%1,%2\n"
" jl 0b"
#else /* CONFIG_64BIT */
" lg %0,%2\n"
"0: lgr %1,%0\n"
" agr %1,%4\n"
" csg %0,%1,%2\n"
" jl 0b"
#endif /* CONFIG_64BIT */
: "=&d" (old), "=&d" (new), "=Q" (sem->count)
: "Q" (sem->count), "d" (delta)
: "cc", "memory");
return new;
}
#endif /* _S390_RWSEM_H */
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