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From: Konstantin Ananyev <konstantin.ananyev@intel.com>
To: dev@dpdk.org
Cc: Konstantin Ananyev <konstantin.ananyev@intel.com>
Subject: [dpdk-dev] [PATCH 1/2] rwlock: introduce 'try' semantics for RD and WR locking
Date: Tue, 13 Nov 2018 17:27:40 +0000	[thread overview]
Message-ID: <1542130061-3702-2-git-send-email-konstantin.ananyev@intel.com> (raw)
In-Reply-To: <1542130061-3702-1-git-send-email-konstantin.ananyev@intel.com>

This patch targets 19.02 release.

Introduce rte_rwlock_read_trylock() and rte_rwlock_write_trylock().
Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
 .../common/include/generic/rte_rwlock.h       | 54 +++++++++++++++++++
 lib/librte_eal/rte_eal_version.map            |  2 +
 2 files 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..7e395781e 100644
--- a/lib/librte_eal/common/include/generic/rte_rwlock.h
+++ b/lib/librte_eal/common/include/generic/rte_rwlock.h
@@ -75,6 +75,33 @@ rte_rwlock_read_lock(rte_rwlock_t *rwl)
 	}
 }
 
+/**
+ * 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 +114,33 @@ rte_rwlock_read_unlock(rte_rwlock_t *rwl)
 	rte_atomic32_dec((rte_atomic32_t *)(intptr_t)&rwl->cnt);
 }
 
+/**
+ * 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;
+	int success = 0;
+
+	while (success == 0) {
+		x = rwl->cnt;
+		/* a lock is held */
+		if (x != 0)
+			return -EBUSY;
+		success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
+					      0, (uint32_t)-1);
+	}
+	return 0;
+}
+
 /**
  * Take a write lock. Loop until the lock is held.
  *
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 3fe78260d..8b1593dd8 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -355,6 +355,8 @@ EXPERIMENTAL {
 	rte_mp_request_async;
 	rte_mp_sendmsg;
 	rte_option_register;
+	rte_rwlock_read_trylock;
+	rte_rwlock_write_trylock;
 	rte_service_lcore_attr_get;
 	rte_service_lcore_attr_reset_all;
 	rte_service_may_be_active;
-- 
2.17.1

  reply	other threads:[~2018-11-13 17:27 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13 17:27 [dpdk-dev] [PATCH 0/2] Add " Konstantin Ananyev
2018-11-13 17:27 ` Konstantin Ananyev [this message]
2018-12-19  6:37   ` [dpdk-dev] [PATCH 1/2] rwlock: introduce " Honnappa Nagarahalli
2018-12-19  8:30     ` Gavin Hu (Arm Technology China)
2018-12-19 10:28     ` Mattias Rönnblom
2018-12-19 10:56       ` Ananyev, Konstantin
2018-12-19 11:00         ` Bruce Richardson
2018-12-19 12:41           ` Ananyev, Konstantin
2018-12-19 15:11     ` Honnappa Nagarahalli
2018-12-19 16:27       ` Ananyev, Konstantin
2018-11-13 17:27 ` [dpdk-dev] [PATCH 2/2] test: add new test-cases for rwlock autotest Konstantin Ananyev
2018-12-19  8:28   ` Gavin Hu (Arm Technology China)
2018-12-19  2:39 ` [dpdk-dev] [PATCH 0/2] Add 'try' semantics for RD and WR locking Thomas Monjalon
2018-12-19 18:07 ` [dpdk-dev] [PATCH v2 " Konstantin Ananyev
2018-12-19 19:53   ` Thomas Monjalon
2018-12-19 18:07 ` [dpdk-dev] [PATCH v2 1/2] rwlock: introduce " Konstantin Ananyev
2018-12-19 18:07 ` [dpdk-dev] [PATCH v2 2/2] test: add new test-cases for rwlock autotest Konstantin Ananyev

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