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author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/arch/s390/include/asm/rwsem.h | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/arch/s390/include/asm/rwsem.h')
-rw-r--r-- | kernel/arch/s390/include/asm/rwsem.h | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/kernel/arch/s390/include/asm/rwsem.h b/kernel/arch/s390/include/asm/rwsem.h new file mode 100644 index 000000000..4b43ee7e6 --- /dev/null +++ b/kernel/arch/s390/include/asm/rwsem.h @@ -0,0 +1,237 @@ +#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 + +#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L +#define RWSEM_ACTIVE_BIAS 0x0000000000000001L +#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL +#define RWSEM_WAITING_BIAS (-0x0000000100000000L) +#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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " aghi %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " 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:" + : "=&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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " ag %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " lg %0,%1\n" + "0: ltgr %0,%0\n" + " jnz 1f\n" + " csg %0,%3,%1\n" + " jl 0b\n" + "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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " aghi %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " ag %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " ag %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " agr %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&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( + " lg %0,%2\n" + "0: lgr %1,%0\n" + " agr %1,%4\n" + " csg %0,%1,%2\n" + " jl 0b" + : "=&d" (old), "=&d" (new), "=Q" (sem->count) + : "Q" (sem->count), "d" (delta) + : "cc", "memory"); + return new; +} + +#endif /* _S390_RWSEM_H */ |