vhost: add spdk_vhost_session_start_done/stop_done

Split spdk_vhost_session_event_done() into two separate
functions. This is just a preparation for the next patch.

Change-Id: I05e046e4b963387f058d2b822d7493c761eebbbb
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/448228
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>

lib/vhost/vhost.c

@@ -872,8 +872,8 @@ spdk_vhost_allocate_reactor(struct spdk_cpuset *cpumask)
 	return selected_core;
 }
 
-void
-spdk_vhost_session_event_done(struct spdk_vhost_session *vsession, int response)
+static void
+complete_session_event(struct spdk_vhost_session *vsession, int response)
 {
 	struct spdk_vhost_session_fn_ctx *ctx = vsession->event_ctx;
 
@@ -881,6 +881,18 @@ spdk_vhost_session_event_done(struct spdk_vhost_session *vsession, int response)
 	sem_post(&ctx->sem);
 }
 
+void
+spdk_vhost_session_start_done(struct spdk_vhost_session *vsession, int response)
+{
+	complete_session_event(vsession, response);
+}
+
+void
+spdk_vhost_session_stop_done(struct spdk_vhost_session *vsession, int response)
+{
+	complete_session_event(vsession, response);
+}
+
 static void
 spdk_vhost_event_cb(void *arg1, void *arg2)
 {

lib/vhost/vhost_blk.c

@@ -722,7 +722,7 @@ spdk_vhost_blk_start_cb(struct spdk_vhost_dev *vdev,
 	SPDK_INFOLOG(SPDK_LOG_VHOST, "Started poller for vhost controller %s on lcore %d\n",
 		     vdev->name, vsession->lcore);
 out:
-	spdk_vhost_session_event_done(vsession, rc);
+	spdk_vhost_session_start_done(vsession, rc);
 	return rc;
 }
 
@@ -772,7 +772,7 @@ destroy_session_poller_cb(void *arg)
 
 	free_task_pool(bvsession);
 	spdk_poller_unregister(&bvsession->stop_poller);
-	spdk_vhost_session_event_done(vsession, 0);
+	spdk_vhost_session_stop_done(vsession, 0);
 
 	spdk_vhost_unlock();
 	return -1;
@@ -796,7 +796,7 @@ spdk_vhost_blk_stop_cb(struct spdk_vhost_dev *vdev,
 	return 0;
 
 err:
-	spdk_vhost_session_event_done(vsession, -1);
+	spdk_vhost_session_stop_done(vsession, -1);
 	return -1;
 }
 

lib/vhost/vhost_internal.h

@@ -318,13 +318,13 @@ void spdk_vhost_dev_foreach_session(struct spdk_vhost_dev *dev,
 				    spdk_vhost_session_fn fn, void *arg);
 
 /**
- * Call the provided function on the session's lcore and block until
- * spdk_vhost_session_event_done() is called.
+ * Call a function on the provided session's lcore and block until either
+ * spdk_vhost_session_start_done() or spdk_vhost_session_stop_done()
+ * is called.
  *
  * This must be called under the global vhost mutex, which this function
- * will unlock for the time it's waiting. This makes it prone to data races,
- * so practically it is only useful for session start/stop and still
- * has to be used with extra caution.
+ * will unlock for the time it's waiting. It's meant to be called only
+ * from start/stop session callbacks.
  *
  * \param vsession vhost session
  * \param cb_fn the function to call. The void *arg parameter in cb_fn
@@ -335,17 +335,36 @@ void spdk_vhost_dev_foreach_session(struct spdk_vhost_dev *dev,
  * \return return the code passed to spdk_vhost_session_event_done().
  */
 int spdk_vhost_session_send_event(struct spdk_vhost_session *vsession,
-				  spdk_vhost_session_fn cb_fn, unsigned timeout_sec, const char *errmsg);
+				  spdk_vhost_session_fn cb_fn, unsigned timeout_sec,
+				  const char *errmsg);
 
 /**
- * Finish a blocking spdk_vhost_session_send_event() call.
+ * Finish a blocking spdk_vhost_session_send_event() call and finally
+ * start the session. This must be called on the target lcore, which
+ * will now receive all session-related messages (e.g. from
+ * spdk_vhost_dev_foreach_session()).
+ *
+ * Must be called under the global vhost lock.
+ *
+ * \param vsession vhost session
+ * \param response return code
+ */
+void spdk_vhost_session_start_done(struct spdk_vhost_session *vsession, int response);
+
+/**
+ * Finish a blocking spdk_vhost_session_send_event() call and finally
+ * stop the session. This must be called on the session's lcore which
+ * used to receive all session-related messages (e.g. from
+ * spdk_vhost_dev_foreach_session()).
+ *
+ * Must be called under the global vhost lock.
  *
  * Must be called under the global vhost mutex.
  *
  * \param vsession vhost session
  * \param response return code
  */
-void spdk_vhost_session_event_done(struct spdk_vhost_session *vsession, int response);
+void spdk_vhost_session_stop_done(struct spdk_vhost_session *vsession, int response);
 
 struct spdk_vhost_session *spdk_vhost_session_find_by_vid(int vid);
 void spdk_vhost_session_install_rte_compat_hooks(struct spdk_vhost_session *vsession);

lib/vhost/vhost_nvme.c

@@ -1106,7 +1106,7 @@ spdk_vhost_nvme_start_cb(struct spdk_vhost_dev *vdev,
 	/* Start the NVMe Poller */
 	nvme->requestq_poller = spdk_poller_register(nvme_worker, nvme, 0);
 
-	spdk_vhost_session_event_done(vsession, 0);
+	spdk_vhost_session_start_done(vsession, 0);
 	return 0;
 }
 
@@ -1186,7 +1186,7 @@ destroy_device_poller_cb(void *arg)
 	nvme->dataplane_started = false;
 
 	spdk_poller_unregister(&nvme->stop_poller);
-	spdk_vhost_session_event_done(nvme->vsession, 0);
+	spdk_vhost_session_stop_done(nvme->vsession, 0);
 
 	spdk_vhost_unlock();
 	return -1;
@@ -1199,7 +1199,7 @@ spdk_vhost_nvme_stop_cb(struct spdk_vhost_dev *vdev,
 	struct spdk_vhost_nvme_dev *nvme = to_nvme_dev(vdev);
 
 	if (nvme == NULL) {
-		spdk_vhost_session_event_done(vsession, -1);
+		spdk_vhost_session_stop_done(vsession, -1);
 		return -1;
 	}
 

lib/vhost/vhost_scsi.c

@@ -1314,7 +1314,7 @@ spdk_vhost_scsi_start_cb(struct spdk_vhost_dev *vdev,
 					 MGMT_POLL_PERIOD_US);
 	}
 out:
-	spdk_vhost_session_event_done(vsession, rc);
+	spdk_vhost_session_start_done(vsession, rc);
 	return rc;
 }
 
@@ -1387,7 +1387,7 @@ destroy_session_poller_cb(void *arg)
 	free_task_pool(svsession);
 
 	spdk_poller_unregister(&svsession->stop_poller);
-	spdk_vhost_session_event_done(vsession, 0);
+	spdk_vhost_session_stop_done(vsession, 0);
 
 	spdk_vhost_unlock();
 	return -1;