rethook: Reject getting a rethook if RCU is not watching
Since the rethook_recycle() will involve the call_rcu() for reclaiming the rethook_instance, the rethook must be set up at the RCU available context (non idle). This rethook_recycle() in the rethook trampoline handler is inevitable, thus the RCU available check must be done before setting the rethook trampoline. This adds a rcu_is_watching() check in the rethook_try_get() so that it will return NULL if it is called when !rcu_is_watching(). Fixes: 54ecbe6f ("rethook: Add a generic return hook") Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/165461827269.280167.7379263615545598958.stgit@devnote2
Showing
Please register or sign in to comment