[Qemu-devel] [PATCH] Check for TUNSETOFFLOAD support before trying to enable offload features

[Pierre Riteau]

This avoids the "TUNSETOFFLOAD ioctl() failed: Invalid argument" message
on kernels without TUNSETOFFLOAD support.

Signed-off-by: Pierre Riteau <pierre.rit...@irisa.fr>
---
 net/tap-linux.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/net/tap-linux.c b/net/tap-linux.c
index 0f621a2..e038e1a 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -129,6 +129,11 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
 {
     unsigned int offload = 0;
 
+    /* Check if our kernel supports TUNSETOFFLOAD */
+    if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
+        return;
+    }
+
     if (csum) {
         offload |= TUN_F_CSUM;
         if (tso4)
-- 
1.6.5