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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.0 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2024-04-08 at 10:09 +0200, Benjamin Tissoires wrote: > Now that we have bpf_timer_set_sleepable_cb() available and working, we > can tag the attached callback as sleepable, and let the verifier check > in the correct context the calls and kfuncs. >=20 > Signed-off-by: Benjamin Tissoires >=20 > --- I think this patch is fine with one nit regarding in_sleepable(). Acked-by: Eduard Zingerman > @@ -5279,7 +5281,8 @@ static int map_kptr_match_type(struct bpf_verifier_= env *env, > =20 > static bool in_sleepable(struct bpf_verifier_env *env) > { > - return env->prog->sleepable; > + return env->prog->sleepable || > + (env->cur_state && env->cur_state->in_sleepable); > } Sorry, I already raised this before. As far as I understand the 'env->cur_state' check is needed because this function is used from do_misc_fixups(): if (is_storage_get_function(insn->imm)) { if (!in_sleepable(env) || env->insn_aux_data[i + delta].storage_get_func_atomic) insn_buf[0] =3D BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_ATOMIC); else insn_buf[0] =3D BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL); insn_buf[1] =3D *insn; cnt =3D 2; ... } For a timer callback function 'env->prog->sleepable' would be false. Which means that inside sleepable callback function GFP_ATOMIC would be used in cases where GFP_KERNEL would be sufficient. An alternative would be to check (and set) sleepable flag not for a full program but for a subprogram. Whether or not this is something worth addressing I don't know. [...]