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([2620:10d:c092:500::5:fc0d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45a1c74876csm173178465e9.14.2025.08.18.06.36.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Aug 2025 06:36:20 -0700 (PDT) Message-ID: <67ae2d13-ce55-4593-816c-31674b7445b0@gmail.com> Date: Mon, 18 Aug 2025 14:36:19 +0100 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next v2 3/4] bpf: task work scheduling kfuncs To: Jiri Olsa Cc: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com, eddyz87@gmail.com, memxor@gmail.com, Mykyta Yatsenko References: <20250815192156.272445-1-mykyta.yatsenko5@gmail.com> <20250815192156.272445-4-mykyta.yatsenko5@gmail.com> Content-Language: en-US From: Mykyta Yatsenko In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/15/25 23:00, Jiri Olsa wrote: > On Fri, Aug 15, 2025 at 08:21:55PM +0100, Mykyta Yatsenko wrote: > > SNIP > >> void bpf_task_work_cancel_and_free(void *val) >> { >> + struct bpf_task_work *tw = val; >> + struct bpf_task_work_context *ctx; >> + enum bpf_task_work_state state; >> + >> + /* No need do rcu_read_lock as no other codepath can reset this pointer */ >> + ctx = unrcu_pointer(xchg((struct bpf_task_work_context __force __rcu **)&tw->ctx, NULL)); >> + if (!ctx) >> + return; >> + state = xchg(&ctx->state, BPF_TW_FREED); >> + >> + switch (state) { >> + case BPF_TW_SCHEDULED: >> + /* If we can't cancel task work, rely on task work callback to free the context */ >> + if (!task_work_cancel_match(ctx->task, task_work_match, ctx)) >> + break; >> + bpf_task_work_context_reset(ctx); >> + fallthrough; >> + case BPF_TW_STANDBY: >> + call_rcu_tasks_trace(&ctx->rcu, bpf_task_work_context_free); >> + break; >> + /* In all below cases scheduling logic should detect context state change and cleanup */ >> + case BPF_TW_SCHEDULING: >> + case BPF_TW_PENDING: >> + case BPF_TW_RUNNING: >> + default: >> + break; >> + } >> } >> >> BTF_KFUNCS_START(generic_btf_ids) >> @@ -3769,6 +4017,8 @@ BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL) >> BTF_ID_FLAGS(func, bpf_rbtree_root, KF_RET_NULL) >> BTF_ID_FLAGS(func, bpf_rbtree_left, KF_RET_NULL) >> BTF_ID_FLAGS(func, bpf_rbtree_right, KF_RET_NULL) >> +BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_TRUSTED_ARGS) >> +BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_TRUSTED_ARGS) > hi, > I'd like to use that with uprobes, could we add it to common_kfunc_set? > I tried it with uprobe and it seems to work nicely > > thanks, > jirka I'll move these kfuncs into common_kfunc_set, in the next version. > > ---- > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > index 346ae8fd3ada..b5d52168ba77 100644 > --- a/kernel/bpf/helpers.c > +++ b/kernel/bpf/helpers.c > @@ -4129,6 +4129,8 @@ BTF_ID_FLAGS(func, bpf_strnstr); > BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU) > #endif > BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_TRUSTED_ARGS) > +BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_TRUSTED_ARGS) > +BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_TRUSTED_ARGS) > BTF_KFUNCS_END(common_btf_ids) > > static const struct btf_kfunc_id_set common_kfunc_set = {