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, 0 deletions

diff --git a/block-raw-posix.c b/block-raw-posix.c
index 2875fa1bfc..267d6c07bd 100644
--- a/block-raw-posix.c
+++ b/block-raw-posix.c
@@ -584,6 +584,10 @@ static int posix_aio_init(void)
     
     s->first_aio = NULL;
     s->fd = qemu_signalfd(&mask);
+    if (s->fd == -1) {
+        fprintf(stderr, "failed to create signalfd\n");
+        return -errno;
+    }
 
     fcntl(s->fd, F_SETFL, O_NONBLOCK);