# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1180016735 -3600
# Node ID 588bd40872ec3fc630079e1402f016d9262dd4f5
# Parent 3ef4a4d8213061fe14d905e89594c99d0b9cb605
ioemu: Attempt to setup tap interface up to 3 times.
As there is a (small) chance that vl.c:tap_open() fails (due to some
sort of race-condition in the Linux kernel, which is noted as a bug in
the source .../net/core/dev.c), we should attempt it again a couple of
times if it doesn't succeed on the first attempt. I think three times
in total is sufficient to avoid the problem.
If tap_open() fails, qemu-dm will exit, which means that the domain
dies - which is not such a good thing when attempting to restore a saved
domain [of course, it would be even worse if it started, but didn't
have networking - because there may not be a way to shut it down
cleanly without network].
Signed-off-by: Mats Petersson <mats.petersson@xxxxxxx>
---
tools/ioemu/vl.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff -r 3ef4a4d82130 -r 588bd40872ec tools/ioemu/vl.c
--- a/tools/ioemu/vl.c Thu May 24 15:21:29 2007 +0100
+++ b/tools/ioemu/vl.c Thu May 24 15:25:35 2007 +0100
@@ -3399,7 +3399,7 @@ static int tap_open(char *ifname, int if
static int tap_open(char *ifname, int ifname_size)
{
struct ifreq ifr;
- int fd, ret;
+ int fd, ret, retries = 0;
fd = open("/dev/net/tun", O_RDWR);
if (fd < 0) {
@@ -3412,7 +3412,9 @@ static int tap_open(char *ifname, int if
pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
else
pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
- ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
+ do {
+ ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
+ } while ((ret != 0) && (retries++ < 3));
if (ret != 0) {
fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual
network emulation\n");
close(fd);
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