As with many syscalls, open() might be interrupted by a signal.

The experienced logfile entry is:

qemu-system-x86_64: -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=libvirt-2-format,id=virtio-disk0,bootindex=2,write-cache=on,serial=1b990c4d13b74a4e90ea: Could not open '/dev/drbd1003': Interrupted system call

Retry it until it is not interrupted by a signal.
FYI, dd has the same kind of loop aroud open().
https://github.com/coreutils/coreutils/blob/1ae98dbda7322427e8226356fd110d2553f5fac9/src/dd.c#L1294-L1299

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
---
 util/osdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/util/osdep.c b/util/osdep.c
index 770369831b..13a09d0dd5 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -295,9 +295,9 @@ static int qemu_open_cloexec(const char *name, int flags, mode_t mode)
 {
     int ret;
 #ifdef O_CLOEXEC
-    ret = open(name, flags | O_CLOEXEC, mode);
+    ret = RETRY_ON_EINTR(open(name, flags | O_CLOEXEC, mode));
 #else
-    ret = open(name, flags, mode);
+    ret = RETRY_ON_EINTR(open(name, flags, mode));
     if (ret >= 0) {
         qemu_set_cloexec(ret);
     }
-- 
2.45.2