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Wed, 14 Oct 2026 14:43:26 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 14 Oct 2026 23:43:24 +0200 To: Leon Hwang Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Emil Tsalapatis , Ihor Solodrai , Quentin Monnet , Shuah Khan , Mykyta Yatsenko , Avinash Duduskar , Anton Protopopov , Amery Hung , Jordan Rife , Rong Tao , Eyal Birger , Pu Lehui , Jingguo Tan , Lin Ma , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH bpf-next v2 01/21] bpf: Initialize ftrace_managed in bpf_trampoline_get() Message-ID: References: <20261012154024.29423-1-leon.hwang@linux.dev> <20261012154024.29423-2-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261012154024.29423-2-leon.hwang@linux.dev> On Mon, Oct 12, 2026 at 11:40:03PM +0800, Leon Hwang wrote: > A trampoline managed by ftrace is determined by its target, that said > ftrace_managed is already known when the trampoline is initialized. so, > set 'ftrace_managed = tr->ip != 0' in bpf_trampoline_get() instead of > relying on the first regular or tracing_multi attachment to set it. > > This makes the backend selection independent of attachment order and keeps > the registration callbacks focused on installing the trampoline. > > No functional change intended. > > Signed-off-by: Leon Hwang Acked-by: Jiri Olsa jirka > --- > kernel/bpf/trampoline.c | 11 ++--------- > 1 file changed, 2 insertions(+), 9 deletions(-) > > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > index 24edb59238f3..17f2a8133f61 100644 > --- a/kernel/bpf/trampoline.c > +++ b/kernel/bpf/trampoline.c > @@ -475,18 +475,11 @@ static int register_fentry(struct bpf_trampoline *tr, struct bpf_tramp_image *im > void *data __maybe_unused) > { > void *new_addr = im->image; > - void *ip = tr->func.addr; > - unsigned long faddr; > int ret; > > - faddr = ftrace_location((unsigned long)ip); > - if (faddr) { > + if (tr->func.ftrace_managed) { > if (!tr->fops) > return -ENOTSUPP; > - tr->func.ftrace_managed = true; > - } > - > - if (tr->func.ftrace_managed) { > ret = direct_ops_add(tr, new_addr); > } else { > ret = bpf_trampoline_update_fentry(tr, 0, NULL, new_addr); > @@ -1286,6 +1279,7 @@ struct bpf_trampoline *bpf_trampoline_get(u64 key, > > memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel)); > tr->func.addr = (void *)tgt_info->tgt_addr; > + tr->func.ftrace_managed = tr->ip != 0; > out: > trampoline_unlock(tr); > return tr; > @@ -1649,7 +1643,6 @@ static int register_fentry_multi(struct bpf_trampoline *tr, struct bpf_tramp_ima > if (bpf_trampoline_use_jmp(tr->flags)) > addr = ftrace_jmp_set(addr); > > - tr->func.ftrace_managed = true; > ftrace_hash_add(data->reg, data->entry, ip, addr); > tr->cur_image = im; > return 0; > -- > 2.55.0 >