PPC: e500: Only create dt entries for existing serial ports

[mirror_qemu.git] / coroutine-win32.c

diff --git a/coroutine-win32.c b/coroutine-win32.c
index edc1f72c1823416a05e48d5ee1c5361285214bf0..17ace37deeb33a19d100f64e86c9ac780e4cd8bc 100644 (file)
--- a/coroutine-win32.c
+++ b/coroutine-win32.c
@@ -36,8 +36,17 @@ typedef struct
 static __thread CoroutineWin32 leader;
 static __thread Coroutine *current;
 
-CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
-                                      CoroutineAction action)
+/* This function is marked noinline to prevent GCC from inlining it
+ * into coroutine_trampoline(). If we allow it to do that then it
+ * hoists the code to get the address of the TLS variable "current"
+ * out of the while() loop. This is an invalid transformation because
+ * the SwitchToFiber() call may be called when running thread A but
+ * return in thread B, and so we might be in a different thread
+ * context each time round the loop.
+ */
+CoroutineAction __attribute__((noinline))
+qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
+                      CoroutineAction action)
 {
     CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
     CoroutineWin32 *to = DO_UPCAST(CoroutineWin32, base, to_);