[PATCH v2] add function spin_event_timeout()

Timur Tabi
2009-03-09T15:18:40Z

The function spin_event_timeout() takes a condition and timeout value
(in jiffies) as parameters. It spins until either the condition is true
or the timeout expires. It returns non-zero if the condition is true,
zero otherwise.

Signed-off-by: Timur Tabi <timur@freescale.com>
---

v2: changes based on feedback

include/linux/delay.h | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/include/linux/delay.h b/include/linux/delay.h
index fd832c6..235ca25 100644
--- a/include/linux/delay.h
+++ b/include/linux/delay.h
@@ -51,4 +51,26 @@ static inline void ssleep(unsigned int seconds)
msleep(seconds * 1000);
}

+/**
+ * spin_event_timeout - spin until a condition gets true or a timeout elapses
+ * @condition: a C expression for the event to wait for
+ * @timeout: timeout, in jiffies
+ *
+ * The process spins until the @condition evaluates to true or the @timeout
+ * elapses.
+ *
+ * The function returns non-zero if the @condition evaluated to true, or
+ * zero if the @timeout elapsed. If both occurs (e.g. the loop was
+ * pre-empted and the @condition became true in the meantime, but when the
+ * loop resumed the @timeout had already elapsed), then non-zero will be
+ * returned.
+ */
+#define spin_event_timeout(condition, timeout) \
+({ \
+ unsigned long __timeout = jiffies + (timeout); \
+ while (!(condition) && time_before(jiffies, __timeout)) \
+ cpu_relax(); \
+ (condition); \
+})
+
#endif /* defined(_LINUX_DELAY_H) */
--
1.6.1.3