coroutine-ucontext: Help valgrind understand coroutines

valgrind tends to get confused and report false positives when you
switch stacks and don't tell it about it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/configure b/configure
index 0a3896e757..cef0a71a27 100755
--- a/configure
+++ b/configure
@@ -2871,6 +2871,22 @@ if compile_prog "" "" ; then
 fi
 
 ########################################
+# check if we have valgrind/valgrind.h
+
+valgrind_h=no
+cat > $TMPC << EOF
+#include <valgrind/valgrind.h>
+#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+int main(void) {
+  VALGRIND_STACK_DEREGISTER(0);
+  return 0;
+}
+EOF
+if compile_prog "" "" ; then
+    valgrind_h=yes
+fi
+
+########################################
 # check if environ is declared
 
 has_environ=no
@@ -3379,6 +3395,10 @@ if test "$linux_magic_h" = "yes" ; then
   echo "CONFIG_LINUX_MAGIC_H=y" >> $config_host_mak
 fi
 
+if test "$valgrind_h" = "yes" ; then
+  echo "CONFIG_VALGRIND_H=y" >> $config_host_mak
+fi
+
 if test "$has_environ" = "yes" ; then
   echo "CONFIG_HAS_ENVIRON=y" >> $config_host_mak
 fi