Re: [PATCH v2 15/15] kprobes: Free kretprobe_instance with rcu callback

peterz
2020-08-27T15:10:41Z

On Thu, Aug 27, 2020 at 08:37:49PM +0900, Masami Hiramatsu wrote:
> Free kretprobe_instance with rcu callback instead of directly
> freeing the object in the kretprobe handler context.
>
> This will make kretprobe run safer in NMI context.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> include/linux/kprobes.h | 3 ++-
> kernel/kprobes.c | 25 ++++++-------------------
> 2 files changed, 8 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 46a7afcf5ec0..97557f820d9b 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -160,6 +160,7 @@ struct kretprobe_instance {
> struct kretprobe *rp;
> kprobe_opcode_t *ret_addr;
> struct task_struct *task;
> + struct rcu_head rcu;
> void *fp;
> char data[];
> };

You can stick the rcu_head in a union with hlist.