[Stable-10.0.10 057/107] serial COM: windows serial COM PollingFunc don't sleep

[Michael Tokarev]

From: Werner de Carne <wer...@carne.de>

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1802
Signed-off-by: Werner de Carne <wer...@carne.de>
[ Marc-André - indentation fixes ]
Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Message-ID: <20230807201443.2668-1-wer...@carne.de>
(cherry picked from commit 7437b3eab6af1d31bb7fdfb3ac4e0a4de6ada50b)
Signed-off-by: Michael Tokarev <m...@tls.msk.ru>

diff --git a/chardev/char-win.c b/chardev/char-win.c
index d4fb44c4dc..a17c36cda6 100644
--- a/chardev/char-win.c
+++ b/chardev/char-win.c
@@ -28,7 +28,7 @@
 #include "qapi/error.h"
 #include "chardev/char-win.h"
 
-static void win_chr_read(Chardev *chr, DWORD len)
+static int win_chr_read(Chardev *chr, DWORD len)
 {
     WinChardev *s = WIN_CHARDEV(chr);
     int max_size = qemu_chr_be_can_write(chr);
@@ -40,7 +40,7 @@ static void win_chr_read(Chardev *chr, DWORD len)
         len = max_size;
     }
     if (len == 0) {
-        return;
+        return 0;
     }
 
     ZeroMemory(&s->orecv, sizeof(s->orecv));
@@ -56,6 +56,8 @@ static void win_chr_read(Chardev *chr, DWORD len)
     if (size > 0) {
         qemu_chr_be_write(chr, buf, size);
     }
+
+    return size > 0 ? 1 : 0;
 }
 
 static int win_chr_serial_poll(void *opaque)
@@ -67,8 +69,9 @@ static int win_chr_serial_poll(void *opaque)
 
     ClearCommError(s->file, &comerr, &status);
     if (status.cbInQue > 0) {
-        win_chr_read(chr, status.cbInQue);
-        return 1;
+        if (win_chr_read(chr, status.cbInQue)) {
+            return 1;
+        }
     }
     return 0;
 }
@@ -147,8 +150,9 @@ int win_chr_pipe_poll(void *opaque)
 
     PeekNamedPipe(s->file, NULL, 0, NULL, &size, NULL);
     if (size > 0) {
-        win_chr_read(chr, size);
-        return 1;
+        if (win_chr_read(chr, size)) {
+            return 1;
+        }
     }
     return 0;
 }
-- 
2.47.3