[PATCH] plugins/hotblocks: Fix potential deadlock in plugin_exit() function

[Cong Liu]

This patch fixes a potential deadlock in the plugin_exit() function of QEMU.
The original code does not release the lock mutex if it is NULL. This patch
adds a check for it being NULL and releases the mutex in that case.

Signed-off-by: Cong Liu <liuco...@kylinos.cn>
---
 contrib/plugins/hotblocks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/contrib/plugins/hotblocks.c b/contrib/plugins/hotblocks.c
index 6b74d25fead6..1f713f1904f3 100644
--- a/contrib/plugins/hotblocks.c
+++ b/contrib/plugins/hotblocks.c
@@ -70,6 +70,8 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
 
         g_list_free(it);
         g_mutex_unlock(&lock);
+    } else {
+        g_mutex_unlock(&lock);
     }
 
     qemu_plugin_outs(report->str);
-- 
2.34.1