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authorPaul E. McKenney <paulmck@kernel.org>2024-02-28 11:17:28 -0800
committerUladzislau Rezki (Sony) <urezki@gmail.com>2024-04-12 11:23:25 +0200
commit1e52af7f023c44859868306fac1a4b6b556cf47b (patch)
tree8b987ba452c39fb944f4ee4d882b1ef079d86cab
parent02b3c5fcdfe46f9c9dd5d3fc199612b13bf47c06 (diff)
bpf: Choose RCU Tasks based on TASKS_RCU rather than PREEMPTION
The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY might see the occasional preemption, and that this preemption just might happen within a trampoline. Therefore, update bpf_tramp_image_put() to choose call_rcu_tasks() based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION. This change might enable further simplifications, but the goal of this effort is to make the code safe, not necessarily optimal. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Yonghong Song <yonghong.song@linux.dev> Cc: KP Singh <kpsingh@kernel.org> Cc: Stanislav Fomichev <sdf@google.com> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Ankur Arora <ankur.a.arora@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <bpf@vger.kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
-rw-r--r--kernel/bpf/trampoline.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index db7599c59c78..88673a4267eb 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -333,7 +333,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im)
int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP,
NULL, im->ip_epilogue);
WARN_ON(err);
- if (IS_ENABLED(CONFIG_PREEMPTION))
+ if (IS_ENABLED(CONFIG_TASKS_RCU))
call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks);
else
percpu_ref_kill(&im->pcref);