On 2016年06月02日 18:44, Arnd Bergmann wrote:
On Thursday, June 2, 2016 6:09:08 PM CEST Pan Xinhui wrote:
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index 54a8e65..eadd7a3 100644
--- a/include/asm-generic/qrwlock.h
+++ b/include/asm-generic/qrwlock.h
@@ -139,7 +139,7 @@ static inline void queued_read_unlock(struct qrwlock *lock)
*/
static inline void queued_write_unlock(struct qrwlock *lock)
{
- smp_store_release((u8 *)&lock->cnts, 0);
+ (void)atomic_sub_return_release(_QW_LOCKED, &lock->cnts);
}
Isn't this more expensive than the existing version?
yes, a little more expensive than the existing version
But does this is generic code, I am not sure how it will impact the performance on other archs.
If you like
we calculate the correct address to set to NULL
say,
static inline void queued_write_unlock(struct qrwlock *lock)
{
u8 *wl = lock;
#ifdef __BIG_ENDIAN
wl += 3;
#endif
smp_store_release(wl, 0);
}
Arnd
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