[dpdk-dev] [PATCH v6 02/19] eal: enable multi process init callback

[Qi Zhang <qi.z.zhang@intel.com>]

Introduce new API rte_eal_register_mp_init that help to register
a callback function which will be invoked right after multi-process
channel be established (rte_mp_channel_init). Typically the API
will be used by other module that want it's mp channel action callbacks
can be registered during rte_eal_init automatically.

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---
 lib/librte_eal/common/eal_common_proc.c | 51 ++++++++++++++++++++++++++++++++-
 lib/librte_eal/common/eal_private.h     |  5 ++++
 lib/librte_eal/common/include/rte_eal.h | 34 ++++++++++++++++++++++
 lib/librte_eal/linuxapp/eal/eal.c       |  2 ++
 4 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/common/eal_common_proc.c b/lib/librte_eal/common/eal_common_proc.c
index f010ef59e..de87925c8 100644
--- a/lib/librte_eal/common/eal_common_proc.c
+++ b/lib/librte_eal/common/eal_common_proc.c
@@ -619,6 +619,42 @@ unlink_sockets(const char *filter)
 	return 0;
 }
 
+struct mp_init_entry {
+	TAILQ_ENTRY(mp_init_entry) next;
+	rte_eal_mp_init_callback_t callback;
+};
+
+TAILQ_HEAD(mp_init_entry_list, mp_init_entry);
+static struct mp_init_entry_list mp_init_entry_list =
+	TAILQ_HEAD_INITIALIZER(mp_init_entry_list);
+
+static int process_mp_init_callbacks(void)
+{
+	struct mp_init_entry *entry;
+	int ret;
+
+	TAILQ_FOREACH(entry, &mp_init_entry_list, next) {
+		ret = entry->callback();
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+int __rte_experimental
+rte_eal_register_mp_init(rte_eal_mp_init_callback_t callback)
+{
+	struct mp_init_entry *entry = calloc(1, sizeof(struct mp_init_entry));
+
+	if (entry == NULL)
+		return -ENOMEM;
+
+	entry->callback = callback;
+	TAILQ_INSERT_TAIL(&mp_init_entry_list, entry, next);
+
+	return 0;
+}
+
 int
 rte_mp_channel_init(void)
 {
@@ -686,7 +722,20 @@ rte_mp_channel_init(void)
 	flock(dir_fd, LOCK_UN);
 	close(dir_fd);
 
-	return 0;
+	return process_mp_init_callbacks();
+}
+
+void rte_mp_init_callback_cleanup(void)
+{
+	struct mp_init_entry *entry;
+
+	while (!TAILQ_EMPTY(&mp_init_entry_list)) {
+		TAILQ_FOREACH(entry, &mp_init_entry_list, next) {
+			TAILQ_REMOVE(&mp_init_entry_list, entry, next);
+			free(entry);
+			break;
+		}
+	}
 }
 
 /**
diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index bdadc4d50..bc230ee23 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -247,6 +247,11 @@ struct rte_bus *rte_bus_find_by_device_name(const char *str);
 int rte_mp_channel_init(void);
 
 /**
+ * Cleanup all mp channel init callbacks.
+ */
+void rte_mp_init_callback_cleanup(void);
+
+/**
  * Internal Executes all the user application registered callbacks for
  * the specific device. It is for DPDK internal user only. User
  * application should not call it directly.
diff --git a/lib/librte_eal/common/include/rte_eal.h b/lib/librte_eal/common/include/rte_eal.h
index 8de5d69e8..506f17f34 100644
--- a/lib/librte_eal/common/include/rte_eal.h
+++ b/lib/librte_eal/common/include/rte_eal.h
@@ -512,6 +512,40 @@ __rte_deprecated
 const char *
 rte_eal_mbuf_default_mempool_ops(void);
 
+/**
+ * Callback function right after multi-process channel be established.
+ * Typical implementation of these functions is to register mp channel
+ * action callbacks
+ *
+ * @return
+ *  - 0 on success.
+ *  - (<0) on failure.
+ */
+typedef int (*rte_eal_mp_init_callback_t)(void);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Register a callback function that will be invoked right after
+ * multi-process channel be established (rte_mp_channel_init). Typically
+ * the function is used by other module that want it's mp channel
+ * action callbacks can be registered during rte_eal_init automatically.
+ *
+ * @note
+ *   This function only take effect when be called before rte_eal_init,
+ *   and all registered callback will be clear during rte_eal_cleanup.
+ *
+ * @param callback
+ *   function be called at that moment.
+ *
+ * @return
+ *  - 0 on success.
+ *  - (<0) on failure.
+ */
+int __rte_experimental
+rte_eal_register_mp_init(rte_eal_mp_init_callback_t callback);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
index 8655b8691..45cccff7e 100644
--- a/lib/librte_eal/linuxapp/eal/eal.c
+++ b/lib/librte_eal/linuxapp/eal/eal.c
@@ -1048,6 +1048,8 @@ int __rte_experimental
 rte_eal_cleanup(void)
 {
 	rte_service_finalize();
+	rte_mp_init_callback_cleanup();
+
 	return 0;
 }
 
-- 
2.13.6