[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>
diff --git a/include/asm-sh/spinlock.h b/include/asm-sh/spinlock.h
index e770b55..846322d 100644
--- a/include/asm-sh/spinlock.h
+++ b/include/asm-sh/spinlock.h
@@ -15,20 +15,11 @@
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*/
-typedef struct {
- volatile unsigned long lock;
-#ifdef CONFIG_PREEMPT
- unsigned int break_lock;
-#endif
-} spinlock_t;
-#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
-
-#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
-
-#define spin_is_locked(x) ((x)->lock != 0)
-#define spin_unlock_wait(x) do { barrier(); } while (spin_is_locked(x))
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
+#define __raw_spin_is_locked(x) ((x)->lock != 0)
+#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
+#define __raw_spin_unlock_wait(x) \
+ do { cpu_relax(); } while (__raw_spin_is_locked(x))
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
@@ -36,7 +27,7 @@
*
* We make no fairness assumptions. They have a cost.
*/
-static inline void _raw_spin_lock(spinlock_t *lock)
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
__asm__ __volatile__ (
"1:\n\t"
@@ -49,14 +40,14 @@
);
}
-static inline void _raw_spin_unlock(spinlock_t *lock)
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
assert_spin_locked(lock);
lock->lock = 0;
}
-#define _raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
+#define __raw_spin_trylock(x) (!test_and_set_bit(0, &(x)->lock))
/*
* Read-write spinlocks, allowing multiple readers but only one writer.
@@ -66,51 +57,40 @@
* needs to get a irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*/
-typedef struct {
- spinlock_t lock;
- atomic_t counter;
-#ifdef CONFIG_PREEMPT
- unsigned int break_lock;
-#endif
-} rwlock_t;
-#define RW_LOCK_BIAS 0x01000000
-#define RW_LOCK_UNLOCKED (rwlock_t) { { 0 }, { RW_LOCK_BIAS } }
-#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while (0)
-
-static inline void _raw_read_lock(rwlock_t *rw)
+static inline void __raw_read_lock(raw_rwlock_t *rw)
{
- _raw_spin_lock(&rw->lock);
+ __raw_spin_lock(&rw->lock);
atomic_inc(&rw->counter);
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
}
-static inline void _raw_read_unlock(rwlock_t *rw)
+static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
- _raw_spin_lock(&rw->lock);
+ __raw_spin_lock(&rw->lock);
atomic_dec(&rw->counter);
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
}
-static inline void _raw_write_lock(rwlock_t *rw)
+static inline void __raw_write_lock(raw_rwlock_t *rw)
{
- _raw_spin_lock(&rw->lock);
+ __raw_spin_lock(&rw->lock);
atomic_set(&rw->counter, -1);
}
-static inline void _raw_write_unlock(rwlock_t *rw)
+static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
atomic_set(&rw->counter, 0);
- _raw_spin_unlock(&rw->lock);
+ __raw_spin_unlock(&rw->lock);
}
-#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
+#define __raw_read_trylock(lock) generic__raw_read_trylock(lock)
-static inline int _raw_write_trylock(rwlock_t *rw)
+static inline int __raw_write_trylock(raw_rwlock_t *rw)
{
if (atomic_sub_and_test(RW_LOCK_BIAS, &rw->counter))
return 1;
@@ -121,4 +101,3 @@
}
#endif /* __ASM_SH_SPINLOCK_H */
-