diff mbox series

[v4,2/3] util/main-loop: Avoid adding the same HANDLE twice

Message ID 20221019102015.2441622-2-bmeng.cn@gmail.com (mailing list archive)
State New, archived
Headers show
Series [v4,1/3] util/main-loop: Fix maximum number of wait objects for win32 | expand

Commit Message

Bin Meng Oct. 19, 2022, 10:20 a.m. UTC
From: Bin Meng <bin.meng@windriver.com>

Fix the logic in qemu_add_wait_object() to avoid adding the same
HANDLE twice, as the behavior is undefined when passing an array
that contains same HANDLEs to WaitForMultipleObjects() API.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

(no changes since v3)

Changes in v3:
- new patch: avoid adding the same HANDLE twice

 include/qemu/main-loop.h |  2 ++
 util/main-loop.c         | 10 ++++++++++
 2 files changed, 12 insertions(+)

Comments

Philippe Mathieu-Daudé Nov. 1, 2022, 1:40 p.m. UTC | #1
On 19/10/22 12:20, Bin Meng wrote:
> From: Bin Meng <bin.meng@windriver.com>
> 
> Fix the logic in qemu_add_wait_object() to avoid adding the same
> HANDLE twice, as the behavior is undefined when passing an array
> that contains same HANDLEs to WaitForMultipleObjects() API.
> 
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
> ---
> 
> (no changes since v3)
> 
> Changes in v3:
> - new patch: avoid adding the same HANDLE twice
> 
>   include/qemu/main-loop.h |  2 ++
>   util/main-loop.c         | 10 ++++++++++
>   2 files changed, 12 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff mbox series

Patch

diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index aac707d073..3c9a9a982d 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -157,6 +157,8 @@  typedef void WaitObjectFunc(void *opaque);
  * in the main loop's calls to WaitForMultipleObjects.  When the handle
  * is in a signaled state, QEMU will call @func.
  *
+ * If the same HANDLE is added twice, this function returns -1.
+ *
  * @handle: The Windows handle to be observed.
  * @func: A function to be called when @handle is in a signaled state.
  * @opaque: A pointer-size value that is passed to @func.
diff --git a/util/main-loop.c b/util/main-loop.c
index de38876064..10fa74c6e3 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -373,10 +373,20 @@  static WaitObjects wait_objects = {0};
 
 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 {
+    int i;
     WaitObjects *w = &wait_objects;
+
     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
         return -1;
     }
+
+    for (i = 0; i < w->num; i++) {
+        /* check if the same handle is added twice */
+        if (w->events[i] == handle) {
+            return -1;
+        }
+    }
+
     w->events[w->num] = handle;
     w->func[w->num] = func;
     w->opaque[w->num] = opaque;