Make compatfd fallback more robust

Be more friendly when signalfd() fails, and also add configure checks to detect
that syscall(SYS_signalfd) actually works.  malc pointed out that some installs
do not have /usr/include/linux headers that are in sync with the glibc headers
so why SYS_signalfd is defined, it's #defined to _NR_signalfd which is not
defined in the /usr/include/linux header.

While this is a distro bug, it doesn't hurt to do a more thorough job in
detection.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5334 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 4 insertions, 5 deletions

diff --git a/compatfd.c b/compatfd.c
index 519b4d8..cc5ced3 100644
--- a/compatfd.c
+++ b/compatfd.c
@@ -100,11 +100,11 @@ static int qemu_signalfd_compat(const sigset_t *mask)
 
 int qemu_signalfd(const sigset_t *mask)
 {
-#if defined(SYS_signalfd)
+#if defined(CONFIG_signalfd)
     int ret;
 
     ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
-    if (!(ret == -1 && errno == ENOSYS))
+    if (ret != -1)
         return ret;
 #endif
 
@@ -113,15 +113,14 @@ int qemu_signalfd(const sigset_t *mask)
 
 int qemu_eventfd(int *fds)
 {
-#if defined(SYS_eventfd)
+#if defined(CONFIG_eventfd)
     int ret;
 
     ret = syscall(SYS_eventfd, 0);
     if (ret >= 0) {
         fds[0] = fds[1] = ret;
         return 0;
-    } else if (!(ret == -1 && errno == ENOSYS))
-        return ret;
+    }
 #endif
 
     return pipe(fds);