tools/accounting/getdelays.c: fix netlink attribute length

A recent change to the netlink code: 6e237d099fac ("netlink: Relax attr
validation for fixed length types") logs a warning when programs send
messages with invalid attributes (e.g., wrong length for a u32). Yafang
reported this error message for tools/accounting/getdelays.c.

send_cmd() is wrongly adding 1 to the attribute length. As noted in
include/uapi/linux/netlink.h nla_len should be NLA_HDRLEN + payload
length, so drop the +1.

Fixes: 9e06d3f9f6b1 ("per task delay accounting taskstats interface: documentation fix")
Reported-by: Yafang Shao <[e-mail]>
Signed-off-by: David Ahern <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Tested-by: Yafang Shao <[e-mail]>
Cc: Johannes Berg <[e-mail]>
Cc: Shailabh Nagar <[e-mail]>
Cc: <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Linus Torvalds <[e-mail]>

tools/accounting/getdelays.c

···
 	msg.g.version = 0x1;
 	na = (struct nlattr *) GENLMSG_DATA(&msg);
 	na->nla_type = nla_type;
-	na->nla_len = nla_len + 1 + NLA_HDRLEN;
+	na->nla_len = nla_len + NLA_HDRLEN;
 	memcpy(NLA_DATA(na), nla_data, nla_len);
 	msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);