linux-stable-rt/arch/parisc/include/asm/spinlock.h

198 lines
4.6 KiB
C
Raw Normal View History

#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <asm/system.h>
[PATCH] spinlock consolidation This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 15:25:56 +08:00
#include <asm/processor.h>
#include <asm/spinlock_types.h>
static inline int arch_spin_is_locked(arch_spinlock_t *x)
{
volatile unsigned int *a = __ldcw_align(x);
return *a == 0;
}
#define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0)
#define arch_spin_unlock_wait(x) \
do { cpu_relax(); } while (arch_spin_is_locked(x))
static inline void arch_spin_lock_flags(arch_spinlock_t *x,
unsigned long flags)
{
volatile unsigned int *a;
mb();
a = __ldcw_align(x);
while (__ldcw(a) == 0)
while (*a == 0)
if (flags & PSW_SM_I) {
local_irq_enable();
cpu_relax();
local_irq_disable();
} else
cpu_relax();
mb();
}
static inline void arch_spin_unlock(arch_spinlock_t *x)
{
volatile unsigned int *a;
mb();
a = __ldcw_align(x);
*a = 1;
mb();
}
static inline int arch_spin_trylock(arch_spinlock_t *x)
{
volatile unsigned int *a;
int ret;
mb();
a = __ldcw_align(x);
ret = __ldcw(a) != 0;
mb();
return ret;
}
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
* Linux rwlocks are unfair to writers; they can be starved for an indefinite
* time by readers. With care, they can also be taken in interrupt context.
*
* In the PA-RISC implementation, we have a spinlock and a counter.
* Readers use the lock to serialise their access to the counter (which
* records how many readers currently hold the lock).
* Writers hold the spinlock, preventing any readers or other writers from
* grabbing the rwlock.
*/
/* Note that we have to ensure interrupts are disabled in case we're
* interrupted by some other code that wants to grab the same read lock */
static __inline__ void arch_read_lock(arch_rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
arch_spin_lock_flags(&rw->lock, flags);
rw->counter++;
arch_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
/* Note that we have to ensure interrupts are disabled in case we're
* interrupted by some other code that wants to grab the same read lock */
static __inline__ void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned long flags;
local_irq_save(flags);
arch_spin_lock_flags(&rw->lock, flags);
rw->counter--;
arch_spin_unlock(&rw->lock);
local_irq_restore(flags);
}
/* Note that we have to ensure interrupts are disabled in case we're
* interrupted by some other code that wants to grab the same read lock */
static __inline__ int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned long flags;
retry:
local_irq_save(flags);
if (arch_spin_trylock(&rw->lock)) {
rw->counter++;
arch_spin_unlock(&rw->lock);
local_irq_restore(flags);
return 1;
}
local_irq_restore(flags);
/* If write-locked, we fail to acquire the lock */
if (rw->counter < 0)
return 0;
/* Wait until we have a realistic chance at the lock */
while (arch_spin_is_locked(&rw->lock) && rw->counter >= 0)
cpu_relax();
goto retry;
}
/* Note that we have to ensure interrupts are disabled in case we're
* interrupted by some other code that wants to read_trylock() this lock */
static __inline__ void arch_write_lock(arch_rwlock_t *rw)
{
unsigned long flags;
retry:
local_irq_save(flags);
arch_spin_lock_flags(&rw->lock, flags);
if (rw->counter != 0) {
arch_spin_unlock(&rw->lock);
local_irq_restore(flags);
[PATCH] spinlock consolidation This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 15:25:56 +08:00
while (rw->counter != 0)
cpu_relax();
goto retry;
}
rw->counter = -1; /* mark as write-locked */
mb();
local_irq_restore(flags);
}
static __inline__ void arch_write_unlock(arch_rwlock_t *rw)
{
rw->counter = 0;
arch_spin_unlock(&rw->lock);
}
/* Note that we have to ensure interrupts are disabled in case we're
* interrupted by some other code that wants to read_trylock() this lock */
static __inline__ int arch_write_trylock(arch_rwlock_t *rw)
{
unsigned long flags;
int result = 0;
local_irq_save(flags);
if (arch_spin_trylock(&rw->lock)) {
if (rw->counter == 0) {
rw->counter = -1;
result = 1;
} else {
/* Read-locked. Oh well. */
arch_spin_unlock(&rw->lock);
}
}
local_irq_restore(flags);
return result;
}
/*
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
static __inline__ int arch_read_can_lock(arch_rwlock_t *rw)
{
return rw->counter >= 0;
}
/*
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
static __inline__ int arch_write_can_lock(arch_rwlock_t *rw)
{
return !rw->counter;
}
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
#endif /* __ASM_SPINLOCK_H */