[RFC PATCH 7/7] qapi: add I/O hang and I/O hang timeout qapi event

[Ying Fang]

Sometimes hypervisor management tools like libvirt may need to monitor
I/O hang events. Let's report I/O hang and I/O hang timeout event via qapi.

Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Signed-off-by: Ying Fang <fangying1@huawei.com>
---
 block/block-backend.c |  3 +++
 qapi/block-core.json  | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 95b2d6a679..5dc5b11bcc 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2540,6 +2540,7 @@ static bool blk_iohang_handle(BlockBackend *blk, int 
new_status)
             /* Case when I/O Hang is recovered */
             blk->is_iohang_timeout = false;
             blk->iohang_time = 0;
+            qapi_event_send_block_io_hang(false);
         }
         break;
     case BLOCK_IO_HANG_STATUS_HANG:
@@ -2547,12 +2548,14 @@ static bool blk_iohang_handle(BlockBackend *blk, int 
new_status)
             /* Case when I/O hang is first triggered */
             blk->iohang_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
             need_rehandle = true;
+            qapi_event_send_block_io_hang(true);
         } else {
             if (!blk->is_iohang_timeout) {
                 now = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
                 if (now >= (blk->iohang_time + blk->iohang_timeout)) {
                     /* Case when I/O hang is timeout */
                     blk->is_iohang_timeout = true;
+                    qapi_event_send_block_io_hang_timeout(true);
                 } else {
                     /* Case when I/O hang is continued */
                     need_rehandle = true;
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 3c16f1e11d..7bdf75c6d7 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -5535,3 +5535,29 @@
 { 'command': 'blockdev-snapshot-delete-internal-sync',
   'data': { 'device': 'str', '*id': 'str', '*name': 'str'},
   'returns': 'SnapshotInfo' }
+
+##
+# @BLOCK_IO_HANG:
+#
+# Emitted when device I/O hang trigger event begin or end
+#
+# @set: true if I/O hang begin; false if I/O hang end.
+#
+# Since: 5.2
+#
+##
+{ 'event': 'BLOCK_IO_HANG',
+  'data': { 'set': 'bool' }}
+
+##
+# @BLOCK_IO_HANG_TIMEOUT:
+#
+# Emitted when device I/O hang timeout event set or clear
+#
+# @set: true if set; false if clear.
+#
+# Since: 5.2
+#
+##
+{ 'event': 'BLOCK_IO_HANG_TIMEOUT',
+  'data': { 'set': 'bool' }}
-- 
2.23.0