[v1] qemu: send stop event after bdrv_flush_all

[PATCH] qemu: send stop event after bdrv_flush_all

tianren posted 1 patch 11 months, 4 weeks ago

Diff against v2 v3
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git fetch https://github.com/patchew-project/qemu tags/patchew/20231204104559.10243-1-tianren@smartx.com

Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>

There is a newer version of this series

system/cpus.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

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[PATCH] qemu: send stop event after bdrv_flush_all

Posted by tianren 11 months, 4 weeks ago

From: Tianren Zhang <tianren@smartx.com>

The stop process is not finished until bdrv_flush_all
is done. Some users (e.g., libvirt) detects the STOP
event and invokes some lock release logic to revoke
the disk lock held by current qemu when such event is
emitted. In such case, if the bdrv_flush_all is after
the stop event, it's possible that the disk lock is
released while the qemu is still waiting for I/O.
Therefore, it's better to have the stop event generated
after the whole stop process is done.

Change-Id: Ia2f95cd55edfdeb71ee2e04005ac216cfabffa22
Signed-off-by: Tianren Zhang <tianren@smartx.com>
---
 system/cpus.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/system/cpus.c b/system/cpus.c
index a444a747f0..b0421f3e22 100644
--- a/system/cpus.c
+++ b/system/cpus.c
@@ -268,15 +268,16 @@ static int do_vm_stop(RunState state, bool send_stop)
         cpu_disable_ticks();
         pause_all_vcpus();
         vm_state_notify(0, state);
-        if (send_stop) {
-            qapi_event_send_stop();
-        }
     }
 
     bdrv_drain_all();
     ret = bdrv_flush_all();
     trace_vm_stop_flush_all(ret);
 
+    if (runstate_is_running() && send_stop) {
+        qapi_event_send_stop();
+    }
+
     return ret;
 }
 
-- 
2.38.1