Signed-off-by: Ola Liljedahl <[email protected]>
---
(This document/code contribution attached is provided under the terms of
agreement LES-LTM-21309)
Implemented the missing odp_ticketlock_trylock().
platform/linux-generic/odp_ticketlock.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/platform/linux-generic/odp_ticketlock.c
b/platform/linux-generic/odp_ticketlock.c
index 682b01b..6525786 100644
--- a/platform/linux-generic/odp_ticketlock.c
+++ b/platform/linux-generic/odp_ticketlock.c
@@ -34,6 +34,36 @@ void odp_ticketlock_lock(odp_ticketlock_t *ticketlock)
odp_spin();
}
+int odp_ticketlock_trylock(odp_ticketlock_t *tklock)
+{
+ /* We read 'next_ticket' and 'cur_ticket' non-atomically which should
+ * not be a problem as they are not independent of each other.
+ * 'cur_ticket' is always <= to 'next_ticket' and if we see an
+ * older value of 'cur_ticket', this only means the lock will
+ * look busy and trylock will fail. */
+ uint32_t next = odp_atomic_load_u32(&tklock->next_ticket);
+ uint32_t cur = odp_atomic_load_u32(&tklock->cur_ticket);
+ /* First check that lock is available and possible to take without
+ * spinning. */
+ if (next == cur) {
+ /* Then try to take the lock by incrementing 'next_ticket'
+ * but only if it still has the original value which is
+ * equal to 'cur_ticket'.
+ * We don't have to include 'cur_ticket' in the comparison
+ * because it cannot be larger than 'next_ticket' (only
+ * smaller if the lock is busy).
+ * If CAS fails, it means some other thread intercepted and
+ * took a ticket which means the lock is not available
+ * anymore */
+ if (_odp_atomic_u32_cmp_xchg_strong_mm(&tklock->next_ticket,
+ &next,
+ next + 1,
+ _ODP_MEMMODEL_ACQ,
+ _ODP_MEMMODEL_RLX))
+ return 1;
+ }
+ return 0;
+}
void odp_ticketlock_unlock(odp_ticketlock_t *ticketlock)
{
--
1.9.1
_______________________________________________
lng-odp mailing list
[email protected]
http://lists.linaro.org/mailman/listinfo/lng-odp
