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SubjectRe: [patch 1/3] spinlock fix #1, *_can_lock() primitives

* Linus Torvalds <torvalds@osdl.org> wrote:

> I can do ppc64 myself, can others fix the other architectures (Ingo,
> shouldn't the UP case have the read/write_can_lock() cases too? And
> wouldn't you agree that it makes more sense to have the rwlock test
> variants in asm/rwlock.h?):

(untested) ia64 version below. Differs from x86/x64.

Ingo

Signed-off-by: Ingo Molnar <mingo@elte.hu>

--- linux/include/asm-ia64/spinlock.h.orig
+++ linux/include/asm-ia64/spinlock.h
@@ -128,8 +128,27 @@ typedef struct {
#define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 }

#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
-#define rwlock_is_locked(x) (*(volatile int *) (x) != 0)

+/**
+ * read_can_lock - would read_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int read_can_lock(rwlock_t *rw)
+{
+ return *(volatile int *)rw >= 0;
+}
+
+/**
+ * write_can_lock - would write_trylock() succeed?
+ * @lock: the rwlock in question.
+ */
+static inline int write_can_lock(rwlock_t *rw)
+{
+ return *(volatile int *)rw == 0;
+}
+
+ /*
+ * On x86, we implement read-write locks as a 32-bit counter
#define _raw_read_lock(rw) \
do { \
rwlock_t *__read_lock_ptr = (rw); \
-
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