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-rw-r--r--ethtool.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/ethtool.c b/ethtool.c
index b424756..9991ce2 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -33,6 +33,8 @@
#include <sys/utsname.h>
#include <limits.h>
#include <ctype.h>
+#include <assert.h>
+#include <sys/fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
@@ -1417,6 +1419,31 @@ static struct feature_defs *get_feature_defs(struct cmd_context *ctx)
return defs;
}
+static int get_netdev_attr(struct cmd_context *ctx, const char *name,
+ char *buf, size_t buf_len)
+{
+#ifdef TEST_ETHTOOL
+ errno = ENOENT;
+ return -1;
+#else
+ char path[40 + IFNAMSIZ];
+ ssize_t len;
+ int fd;
+
+ len = snprintf(path, sizeof(path), "/sys/class/net/%s/%s",
+ ctx->devname, name);
+ assert(len < sizeof(path));
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return fd;
+ len = read(fd, buf, buf_len - 1);
+ if (len >= 0)
+ buf[len] = 0;
+ close(fd);
+ return len;
+#endif
+}
+
static int do_gdrv(struct cmd_context *ctx)
{
int err;
@@ -1858,6 +1885,20 @@ get_features(struct cmd_context *ctx, const struct feature_defs *defs)
perror("Cannot get device generic features");
else
allfail = 0;
+ } else {
+ /* We should have got VLAN tag offload flags through
+ * ETHTOOL_GFLAGS. However, prior to Linux 2.6.37
+ * they were not exposed in this way - and since VLAN
+ * tag offload was defined and implemented by many
+ * drivers, we shouldn't assume they are off.
+ * Instead, since these feature flag values were
+ * stable, read them from sysfs.
+ */
+ char buf[20];
+ if (get_netdev_attr(ctx, "features", buf, sizeof(buf)) > 0)
+ state->off_flags |=
+ strtoul(buf, NULL, 0) &
+ (ETH_FLAG_RXVLAN | ETH_FLAG_TXVLAN);
}
if (allfail) {