From: Daniel Borkmann <dan...@iogearbox.net>
Date: Mon, 27 Jun 2016 21:38:11 +0200
> Commit dead9f29ddcc ("perf: Fix race in BPF program unregister") moved
> destruction of BPF program from free_event_rcu() callback to __free_event(),
> which is problematic if used with tail calls: if prog A is attached as
> trace event directly, but at the same time present in a tail call map used
> by another trace event program elsewhere, then we need to delay destruction
> via RCU grace period since it can still be in use by the program doing the
> tail call (the prog first needs to be dropped from the tail call map, then
> trace event with prog A attached destroyed, so we get immediate destruction).
>
> Fixes: dead9f29ddcc ("perf: Fix race in BPF program unregister")
> Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
> Acked-by: Alexei Starovoitov <a...@kernel.org>
> Cc: Jann Horn <j...@thejh.net>
Applied and queued up for -stable, thanks Daniel.
