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Thu, 27 Aug 2026 00:11:58 -0700 (PDT) X-Received: by 2002:a05:622a:3ce:b0:527:7a5b:ca67 with SMTP id d75a77b69052e-52e423deda8mr121295541cf.20.1787814717537; Thu, 27 Aug 2026 00:11:57 -0700 (PDT) Received: from localhost ([188.216.77.92]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49b4e2c1af7sm27101205e9.15.2026.08.27.00.11.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Aug 2026 00:11:56 -0700 (PDT) Date: Thu, 27 Aug 2026 09:11:55 +0200 From: Lorenzo Bianconi To: Maxime Chevallier , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Jose Abreu Cc: netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH net] net: stmmac: hold runtime PM reference in setup_tc Message-ID: References: <20260824-stmmac-setup-tc-enable-pm-v1-1-45172d241a4b@oss.qualcomm.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Qit4tLMxBEK2W8qA" Content-Disposition: inline In-Reply-To: <20260824-stmmac-setup-tc-enable-pm-v1-1-45172d241a4b@oss.qualcomm.com> X-Authority-Analysis: v=2.4 cv=NrThtcdJ c=1 sm=1 tr=0 ts=6a8fe33f cx=c_pps a=mPf7EqFMSY9/WdsSgAYMbA==:117 a=WpTaRW6qxYHRGzLzQsVYzg==:17 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_K5XuSEh1TEqbUxoQ0s3:22 a=9R54UkLUAAAA:8 a=EUspDBNiAAAA:8 a=VwQbUJbxAAAA:8 a=LK5SnTVSdOS2cW5lnr8A:9 a=CjuIK1q_8ugA:10 a=_YFSIjxOcyUDFHQV-BYA:9 a=dawVfQjAaf238kedN5IG:22 a=YTcpBFlVQWkNscrzJ_Dz:22 X-Proofpoint-ORIG-GUID: RVdzv8sxrT4DRAwILxDEl3Dy8jiubFPu X-Proofpoint-GUID: RVdzv8sxrT4DRAwILxDEl3Dy8jiubFPu X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI3MDA1OCBTYWx0ZWRfX6YwUP+w/qLjJ mOXofcV00+D7y9iaNQbSABbMll6uhuTdQyVga+UGRh2CWmZXDGJn2xIS8SGo6qVfNpwbY64obhE I8KjXKcb4Sr71ihP1Grcf+GNfarCIsGmLfOValiBgLsfEZUxxkCpmKqKopFU4JK3ihYXVMiVyfa 2EeRdtbjiBn4M469xTZUdTcmEObdG0f96ms7IaEjDiQkggwrNRESSrZvsHN7962FBeU9GvyKTp+ sQHw4qoSiA7O1RxNzOPgyF6q7xLmYC3FAM3ZD9u1JwgHwzUOWb9xVKRdSMkXeeS+Av+EJmbCVjo KCHKkikQDhMlxi4VHG/PoQ3xAEpjf3iqpgu6/6SKyhKuqx6zx/Lj36awcD/UMaALC6SADLntdwc aKhisYBdeG4a24eh5EZuf16LlBD4SRfjQ0mXpPF2cA0dYsYISrzn+EKc4oGQ+bOSNvx4Xs2xko2 JYuogxjlKrYrX0bdRmA== X-Proofpoint-Spam-Info: AW1haW4tMjYwODI3MDA1OCBTYWx0ZWRfX70EHJp3tEZO7 yoTI6etWseC4WVS0JQ0ey2MxVdQ038/EHdBXMM6jKot4YKU6Zu156puxrgyKvA7Cbt6UQrsZjg2 DJjp9fyg7rBfCPMiirEF5M/LCq3BNX8= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-27_03,2026-08-26_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 spamscore=0 adultscore=0 suspectscore=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 clxscore=1015 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608270058 --Qit4tLMxBEK2W8qA Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > The qdisc offload callbacks invoked by stmmac_setup_tc() program > MTL/MAC registers, but they can be reached while the interface is down, > when stmmac_release() has dropped the runtime PM usage counter and the > device may be suspended with its clocks gated. Accessing the registers > in that state can trigger a bus error. >=20 > Hold a runtime PM reference while configuring the register-touching > qdisc offloads (mqprio, cbs and taprio) so the device is active, and its > clocks enabled, whenever the MTL/MAC registers are programmed. >=20 > The TC block callback stmmac_setup_tc_block_cb() programs the MTL/MAC > registers as well, but it runs asynchronously from stmmac_setup_tc(), > outside the runtime PM reference held there. Hold a runtime PM reference > for the whole stmmac_setup_tc_block_cb() call as well, covering the > cls_u32/cls_flower setup and the queue enable/disable accesses. >=20 > No reference is held for the TC_SETUP_BLOCK bookkeeping itself, the > TC_QUERY_CAPS query or the tc-etf path, since none of them touch the > registers synchronously. In particular the block bind/unbind must reach > flow_block_cb_setup_simple() even when the device is suspended, so the > driver never leaves a stale flow_block_cb on its block list. >=20 > Fixes: 1f705bc61aee ("net: stmmac: Add support for CBS QDISC") > Fixes: 4dbbe8dde848 ("net: stmmac: Add support for U32 TC filter using Fl= exible RX Parser") > Signed-off-by: Lorenzo Bianconi > --- > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 34 +++++++++++++++++= +++--- > 1 file changed, 30 insertions(+), 4 deletions(-) >=20 > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/= net/ethernet/stmicro/stmmac/stmmac_main.c > index b2b7d0242dd3..4baf40fb01dc 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -6392,9 +6392,13 @@ static int stmmac_setup_tc_block_cb(enum tc_setup_= type type, void *type_data, > void *cb_priv) > { > struct stmmac_priv *priv =3D cb_priv; > - int ret =3D -EOPNOTSUPP; > + int ret; > =20 > if (!tc_cls_can_offload_and_chain0(priv->dev, type_data)) > + return -EOPNOTSUPP; > + > + ret =3D pm_runtime_resume_and_get(priv->device); > + if (ret < 0) > return ret; > =20 > __stmmac_disable_all_queues(priv); > @@ -6411,6 +6415,8 @@ static int stmmac_setup_tc_block_cb(enum tc_setup_t= ype type, void *type_data, > } > =20 > stmmac_enable_all_queues(priv); > + pm_runtime_put(priv->device); commenting on sashiko's report: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260824-stmmac-setup-t= c-enable-pm-v1-1-45172d241a4b%40oss.qualcomm.com - Dropping the -EOPNOTSUPP initializer of ret changes what this callback returns for tc_setup_type values the driver does not handle. ret is now first assigned by pm_runtime_resume_and_get(), which returns exactly 0 on success - I will fix it in v2 > + > return ret; > } > =20 > @@ -6420,26 +6426,46 @@ static int stmmac_setup_tc(struct net_device *nde= v, enum tc_setup_type type, > void *type_data) > { > struct stmmac_priv *priv =3D netdev_priv(ndev); > + int ret; > =20 > switch (type) { > case TC_QUERY_CAPS: > return stmmac_tc_query_caps(priv, priv, type_data); > case TC_SETUP_QDISC_MQPRIO: > - return stmmac_tc_setup_mqprio(priv, priv, type_data); > + ret =3D pm_runtime_resume_and_get(priv->device); > + if (ret < 0) > + return ret; > + > + ret =3D stmmac_tc_setup_mqprio(priv, priv, type_data); > + break; > case TC_SETUP_BLOCK: > return flow_block_cb_setup_simple(type_data, > &stmmac_block_cb_list, > stmmac_setup_tc_block_cb, > priv, priv, true); > case TC_SETUP_QDISC_CBS: > - return stmmac_tc_setup_cbs(priv, priv, type_data); > + ret =3D pm_runtime_resume_and_get(priv->device); > + if (ret < 0) > + return ret; > + > + ret =3D stmmac_tc_setup_cbs(priv, priv, type_data); > + break; > case TC_SETUP_QDISC_TAPRIO: > - return stmmac_tc_setup_taprio(priv, priv, type_data); > + ret =3D pm_runtime_resume_and_get(priv->device); > + if (ret < 0) > + return ret; > + > + ret =3D stmmac_tc_setup_taprio(priv, priv, type_data); - This is a pre-existing issue, but the patch now explicitly sanctions running taprio (and cls_u32/cls_flower in the block callback) with only the bus/CSR clocks resumed, without the rest of the hardware state those sequences depend on - This is fixed in the following patch: https://lore.kernel.org/netdev/20260825-stmmac-est-reapply-after-open-v= 1-1-dfa80735e0a1@oss.qualcomm.com/ Regards, Lorenzo > + break; > case TC_SETUP_QDISC_ETF: > return stmmac_tc_setup_etf(priv, priv, type_data); > default: > return -EOPNOTSUPP; > } > + > + pm_runtime_put(priv->device); > + > + return ret; > } > =20 > static u16 stmmac_select_queue(struct net_device *dev, struct sk_buff *s= kb, >=20 > --- > base-commit: 7cbfb180945ce529608e4d4e24a6d483699fab1e > change-id: 20260824-stmmac-setup-tc-enable-pm-149aa563d797 >=20 > Best regards, > --=20 > Lorenzo Bianconi >=20 --Qit4tLMxBEK2W8qA Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHQEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCao/jOwAKCRA6cBh0uS2t rDwmAPi5W46YAs2N7ck9ZndK/1g9U+egoj3T61BVVsU5jsTJAP466NaLx5IjYqmy +tu/Ntp3W3JTj5GLfket4cN6CcZcDQ== =DNMW -----END PGP SIGNATURE----- --Qit4tLMxBEK2W8qA--