From 0f0c332992b8a5d2ae7b611b94c4e02ef8d54b97 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Fri, 30 Jan 2026 09:12:07 +0100 Subject: bpf: Allow sleepable programs to use tail calls Allowing sleepable programs to use tail calls. Making sure we can't mix sleepable and non-sleepable bpf programs in tail call map (BPF_MAP_TYPE_PROG_ARRAY) and allowing it to be used in sleepable programs. Sleepable programs can be preempted and sleep which might bring new source of race conditions, but both direct and indirect tail calls should not be affected. Direct tail calls work by patching direct jump to callee into bpf caller program, so no problem there. We atomically switch from nop to jump instruction. Indirect tail call reads the callee from the map and then jumps to it. The callee bpf program can't disappear (be released) from the caller, because it is executed under rcu lock (rcu_read_lock_trace). Signed-off-by: Jiri Olsa Acked-by: Leon Hwang Link: https://lore.kernel.org/r/20260130081208.1130204-2-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 5524f9429e76..3b0ceb759075 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -287,6 +287,7 @@ struct bpf_map_owner { enum bpf_prog_type type; bool jited; bool xdp_has_frags; + bool sleepable; u64 storage_cookie[MAX_BPF_CGROUP_STORAGE_TYPE]; const struct btf_type *attach_func_proto; enum bpf_attach_type expected_attach_type; -- cgit v1.2.3