qemu_signalfd() provides the (effects of the) Linux signalfd() syscall on
platforms that lack it. However, the check for the availability of
signalfd() in configure, and its use in qemu_signalfd() when it *is*
available, are seriously outdated (they date back to 2010-2011).
To wit, the SYS_signalfd-based check in configure can actually fail on at
least modern aarch64 Linux systems that *do* have signalfd().
(SYS_signalfd is deprecated and has been replaced by SYS_signalfd4 (note
the "4"). The signalfd() libc function selects the appropriate system
call.)
We should consider signalfd() accessible as a first class libc function on
platforms that support it. Modernize the related parts in configure and
"util/compatfd.c" (so that we end up with something similar to eventfd()'s
detection).
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
---
configure | 11 ++++++++---
util/compatfd.c | 5 ++---
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/configure b/configure
index 5ea1014..de0d21c 100755
--- a/configure
+++ b/configure
@@ -3280,10 +3280,15 @@ fi
# signalfd probe
signalfd="no"
cat > $TMPC << EOF
-#include <unistd.h>
-#include <sys/syscall.h>
+#include <sys/signalfd.h>
#include <signal.h>
-int main(void) { return syscall(SYS_signalfd, -1, NULL, _NSIG / 8); }
+int main(void)
+{
+ sigset_t s;
+
+ sigfillset(&s);
+ return signalfd(-1, &s, SFD_CLOEXEC);
+}
EOF
if compile_prog "" "" ; then
diff --git a/util/compatfd.c b/util/compatfd.c
index e857150..7983391 100644
--- a/util/compatfd.c
+++ b/util/compatfd.c
@@ -17,7 +17,7 @@
#include "qemu/compatfd.h"
#include "qemu/thread.h"
-#include <sys/syscall.h>
+#include <sys/signalfd.h>
struct sigfd_compat_info
{
@@ -99,9 +99,8 @@ int qemu_signalfd(const sigset_t *mask)
#if defined(CONFIG_SIGNALFD)
int ret;
- ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
+ ret = signalfd(-1, mask, SFD_CLOEXEC);
if (ret != -1) {
- qemu_set_cloexec(ret);
return ret;
}
#endif
--
1.8.3.1
