[Qemu-devel] [PATCH 5/5] pr-manager-helper: report event on connection/disconnection

[Paolo Bonzini]

Let management know if there were any problems communicating with
qemu-pr-helper.  The event is edge-triggered, and is sent every time
the connection status of the pr-manager-helper object changes.

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 qapi/block.json          | 24 ++++++++++++++++++++++++
 scsi/pr-manager-helper.c | 25 +++++++++++++++++++------
 2 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/qapi/block.json b/qapi/block.json
index dc3323c954..1882a8d107 100644
--- a/qapi/block.json
+++ b/qapi/block.json
@@ -334,6 +334,30 @@
 { 'event': 'DEVICE_TRAY_MOVED',
   'data': { 'device': 'str', 'id': 'str', 'tray-open': 'bool' } }
 
+##
+# @PR_MANAGER_STATUS_CHANGED:
+#
+# Emitted whenever the connected status of a persistent reservation
+# manager changes.
+#
+# @id: The QOM path of the PR manager object
+#
+# @connected: true if the PR manager is connected to a backend
+#
+# Since: 2.12
+#
+# Example:
+#
+# <- { "event": "PR_MANAGER_STATUS_CHANGED",
+#      "data": { "id": "/object/pr-helper0",
+#                "connected": true
+#      },
+#      "timestamp": { "seconds": 1519840375, "microseconds": 450486 } }
+#
+##
+{ 'event': 'PR_MANAGER_STATUS_CHANGED',
+  'data': { 'id': 'str', 'connected': 'bool' } }
+
 ##
 # @QuorumOpType:
 #
diff --git a/scsi/pr-manager-helper.c b/scsi/pr-manager-helper.c
index b11481be9e..6643caf4cf 100644
--- a/scsi/pr-manager-helper.c
+++ b/scsi/pr-manager-helper.c
@@ -17,6 +17,7 @@
 #include "io/channel.h"
 #include "io/channel-socket.h"
 #include "pr-helper.h"
+#include "qapi/qapi-events-block.h"
 
 #include <scsi/sg.h>
 
@@ -33,6 +34,7 @@ typedef struct PRManagerHelper {
     PRManager parent;
 
     char *path;
+    char *qom_path;
 
     QemuMutex lock;
     QIOChannel *ioc;
@@ -127,6 +129,8 @@ static int pr_manager_helper_initialize(PRManagerHelper 
*pr_mgr,
         goto out_close;
     }
 
+    qapi_event_send_pr_manager_status_changed(pr_mgr->qom_path, true,
+                                              &error_abort);
     return 0;
 
 out_close:
@@ -142,9 +146,11 @@ static int pr_manager_helper_run(PRManager *p,
 
     uint32_t len;
     PRHelperResponse resp;
+    int sense_len;
     int ret;
     int expected_dir;
     int attempts;
+    bool was_connected = pr_mgr->ioc != NULL;
     uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };
 
     if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {
@@ -222,15 +228,19 @@ static int pr_manager_helper_run(PRManager *p,
         io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
         memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
     }
+    qemu_mutex_unlock(&pr_mgr->lock);
+    return ret;
 
 out:
-    if (ret < 0) {
-        int sense_len = scsi_build_sense(io_hdr->sbp,
-                                         SENSE_CODE(LUN_COMM_FAILURE));
-        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
-        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
-        io_hdr->status = CHECK_CONDITION;
+    if (was_connected) {
+        qapi_event_send_pr_manager_status_changed(pr_mgr->qom_path, false,
+                                                  &error_abort);
     }
+
+    sense_len = scsi_build_sense(io_hdr->sbp, SENSE_CODE(LUN_COMM_FAILURE));
+    io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
+    io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
+    io_hdr->status = CHECK_CONDITION;
     qemu_mutex_unlock(&pr_mgr->lock);
     return ret;
 }
@@ -251,6 +261,8 @@ static void pr_manager_helper_complete(UserCreatable *uc, 
Error **errp)
 {
     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);
 
+    pr_mgr->qom_path = object_get_canonical_path(OBJECT(pr_mgr));
+
     qemu_mutex_lock(&pr_mgr->lock);
     pr_manager_helper_initialize(pr_mgr, errp);
     qemu_mutex_unlock(&pr_mgr->lock);
@@ -276,6 +288,7 @@ static void pr_manager_helper_instance_finalize(Object *obj)
     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 
     object_unref(OBJECT(pr_mgr->ioc));
+    g_free(pr_mgr->qom_path);
     qemu_mutex_destroy(&pr_mgr->lock);
 }
 
-- 
2.17.1