Introduce rte_rwlock_read_trylock() and rte_rwlock_write_trylock().
Signed-off-by: Konstantin Ananyev <konstantin.anan...@intel.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
Reviewed-by: Gavin Hu <gavin...@arm.com>
---
.../common/include/generic/rte_rwlock.h | 56 +++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/lib/librte_eal/common/include/generic/rte_rwlock.h
b/lib/librte_eal/common/include/generic/rte_rwlock.h
index 5751a0e6d..b05d85aee 100644
--- a/lib/librte_eal/common/include/generic/rte_rwlock.h
+++ b/lib/librte_eal/common/include/generic/rte_rwlock.h
@@ -75,6 +75,36 @@ rte_rwlock_read_lock(rte_rwlock_t *rwl)
}
}
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * try to take a read lock.
+ *
+ * @param rwl
+ * A pointer to a rwlock structure.
+ * @return
+ * - zero if the lock is successfully taken
+ * - -EBUSY if lock could not be acquired for reading because a
+ * writer holds the lock
+ */
+static inline __rte_experimental int
+rte_rwlock_read_trylock(rte_rwlock_t *rwl)
+{
+ int32_t x;
+ int success = 0;
+
+ while (success == 0) {
+ x = rwl->cnt;
+ /* write lock is held */
+ if (x < 0)
+ return -EBUSY;
+ success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
+ (uint32_t)x, (uint32_t)(x + 1));
+ }
+ return 0;
+}
+
/**
* Release a read lock.
*
@@ -87,6 +117,32 @@ rte_rwlock_read_unlock(rte_rwlock_t *rwl)
rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
}
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * try to take a write lock.
+ *
+ * @param rwl
+ * A pointer to a rwlock structure.
+ * @return
+ * - zero if the lock is successfully taken
+ * - -EBUSY if lock could not be acquired for writing because
+ * it was already locked for reading or writing
+ */
+static inline __rte_experimental int
+rte_rwlock_write_trylock(rte_rwlock_t *rwl)
+{
+ int32_t x;
+
+ x = rwl->cnt;
+ if (x != 0 || rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
+ 0, (uint32_t)-1) == 0)
+ return -EBUSY;
+
+ return 0;
+}
+
/**
* Take a write lock. Loop until the lock is held.
*
--
2.17.1
