kprobes: initialize before using a hlist

kprobes: initialize before using a hlist

Commit ef53d9c5e ("kprobes: improve kretprobe scalability with hashed
locking") introduced a bug where we can potentially leak
kretprobe_instances since we initialize a hlist head after having used
it.

Initialize the hlist head before using it.

Reported by: Jim Keniston <[email protected]>
Acked-by: Jim Keniston <[email protected]>
Signed-off-by: Ananth N Mavinakayanahalli <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Cc: Srinivasa D S <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>