netlink: rate-limit leftover bytes warning and print process name

netlink: rate-limit leftover bytes warning and print process name

[ Upstream commit bfc5184b69cf9eeb286137640351c650c27f118a ]

Any process is able to send netlink messages with leftover bytes.
Make the warning rate-limited to prevent too much log spam.

The warning is supposed to help find userspace bugs, so print the
triggering command name to implicate the buggy program.

[v2: Use pr_warn_ratelimited instead of printk_ratelimited.]

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Add #include of <linux/sched.h> for definition of struct task_struct,
 as in 3.2 it doesn't get included indirectly on all architectures.  Thanks
 to Guenter Roeck for debugging this.]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>