From 91ca60e01277da2184d9c3f992c440cb5aa264c4 Mon Sep 17 00:00:00 2001 From: Michael Tokarev Date: Wed, 2 Jun 2010 14:33:01 -0300 Subject: [PATCH] give some useful error messages when tap open In net/tap-linux.c, when manipulation of /dev/net/tun fails, it prints (with fprintf) something like this: warning: could not open /dev/net/tun: no virtual network emulation this has 2 issues: 1) it is not a warning really, it's a fatal error (kvm exits after that), 2) there's no indication as of what's actually wrong: printing errno there is helpful. The patch below removes the "warning" prefix, uses %m (since it's linux, %m is available as format modifier), and changes fprintf() to %qemu_error(). Now it prints something like this instead: could not configure /dev/net/tun: Device or resource busy (there are 2 messages like that in the same function) This fixes Debian bug #578154, see http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=578154 Signed-off-by: Michael Tokarev Signed-off-by: Luiz Capitulino Signed-off-by: Anthony Liguori --- net/tap-linux.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/tap-linux.c b/net/tap-linux.c index 03b83012f8..c92983cb53 100644 --- a/net/tap-linux.c +++ b/net/tap-linux.c @@ -33,14 +33,16 @@ #include "qemu-common.h" #include "qemu-error.h" +#define PATH_NET_TUN "/dev/net/tun" + int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required) { struct ifreq ifr; int fd, ret; - TFR(fd = open("/dev/net/tun", O_RDWR)); + TFR(fd = open(PATH_NET_TUN, O_RDWR)); if (fd < 0) { - fprintf(stderr, "warning: could not open /dev/net/tun: no virtual network emulation\n"); + error_report("could not open %s: %m", PATH_NET_TUN); return -1; } memset(&ifr, 0, sizeof(ifr)); @@ -71,7 +73,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d"); ret = ioctl(fd, TUNSETIFF, (void *) &ifr); if (ret != 0) { - fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual network emulation\n"); + error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name); close(fd); return -1; }