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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ijae Kim Subject: [PATCH net] idpf: disable DIM work before freeing q_vectors Date: Mon, 20 Jul 2026 22:58:46 +0900 Message-ID: <20260720135846.76229-1-mhun512@gmail.com> X-Mailer: git-send-email 2.47.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" idpf never drains the Tx/Rx DIM works before freeing the memory they live in. tx_dim and rx_dim are embedded in struct idpf_q_vector, they are queued from the NAPI poll via net_dim(), and idpf_vport_intr_rel() ends with kfree(rsrc->q_vectors). Nothing in the driver cancels them. idpf_tx_dim_work() and idpf_rx_dim_work() then run on freed memory: idpf_vport_intr_write_itr() writes the ITR register through q_vector->intr_reg.tx_itr / rx_itr, void __iomem pointers loaded out of the freed q_vector. No configuration is needed to get there -- IDPF_ITR_IS_DYNAMIC() is defined as (itr_mode) and idpf_vport_alloc() initialises both modes to IDPF_ITR_DYNAMIC. Draining after idpf_vport_intr_napi_dis_all() is not enough on its own. idpf_net_dim() is called from inside the "if (napi_complete_done(napi, work_done))" branch of the poll, and napi_complete_done() has already cleared NAPIF_STATE_SCHED by then. napi_disable_locked() waits only while (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)), so napi_disable() can return while the poll tail is still queueing the work, and a plain cancel_work_sync() would be re-armed behind the drain. Use disable_work_sync(): schedule_work() on a work with a non-zero disable count is dropped by clear_pending_if_disabled() before __queue_work() is reached. Move idpf_init_dim() to idpf_vport_intr_alloc() so the works are initialised on every path that can reach the drain -- the three "goto intr_deinit" sites between idpf_vport_intr_init() and idpf_vport_intr_ena() get there without the enable side having run. Nothing re-enables them: rsrc->q_vectors is freed on every exit from idpf_vport_open() and on every idpf_vport_stop(), so the count dies with the object. It is a race, not a deterministic failure -- net_dim() only schedules once DIM_NEVENTS events have accumulated and the profile index changes. A KASAN ifup/ifdown loop under load is the way to see it. Fixes: c2d548cad150 ("idpf: add TX splitq napi poll support") Fixes: 3a8845af66ed ("idpf: add RX splitq napi poll support") Cc: # see patch description, needs adjustments for= <=3D 6.9 Co-developed-by: Ijae Kim Signed-off-by: Ijae Kim Signed-off-by: Myeonghun Pak --- Found by static analysis; not tested on hardware. Testing by someone at Intel with an idpf device would be very welcome. disable_work_sync() landed in v6.10, which is newer than the commits this fixes, hence the annotation on the stable tag. A backport to older trees needs the work held down another way rather than a cherry-pick; happy to send one if the bot reports a failure. libwx does the same thing in the same order -- napi_disable() then disable_work_sync() on the dim works -- in wx_napi_disable_all(). Based on v7.2-rc2. drivers/net/ethernet/intel/idpf/idpf_txrx.c | 24 +++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethe= rnet/intel/idpf/idpf_txrx.c index 7f9056404f64..cd98674fb648 100644 --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c @@ -4148,6 +4148,26 @@ static void idpf_vport_intr_ena_irq_all(struct idpf_= vport *vport, writel(rsrc->noirq_dyn_ctl_ena, rsrc->noirq_dyn_ctl); } +/** + * idpf_vport_intr_dis_dim_all - Disable DIM work for all q_vectors + * @rsrc: pointer to queue and vector resources + * + * The DIM works are embedded in the q_vector array that + * idpf_vport_intr_rel() frees, and the poll arms them after + * napi_complete_done() has already cleared NAPI_STATE_SCHED. Disable + * rather than just cancel, so that a poll tail still running past + * napi_disable() cannot queue them again behind the drain. + */ +static void idpf_vport_intr_dis_dim_all(struct idpf_q_vec_rsrc *rsrc) +{ + for (u16 v_idx =3D 0; v_idx < rsrc->num_q_vectors; v_idx++) { + struct idpf_q_vector *q_vector =3D &rsrc->q_vectors[v_idx]; + + disable_work_sync(&q_vector->tx_dim.work); + disable_work_sync(&q_vector->rx_dim.work); + } +} + /** * idpf_vport_intr_deinit - Release all vector associations for the vport * @vport: main vport structure @@ -4158,6 +4178,7 @@ void idpf_vport_intr_deinit(struct idpf_vport *vport, { idpf_vport_intr_dis_irq_all(rsrc); idpf_vport_intr_napi_dis_all(rsrc); + idpf_vport_intr_dis_dim_all(rsrc); idpf_vport_intr_napi_del_all(rsrc); idpf_vport_intr_rel_irq(vport, rsrc); } @@ -4238,7 +4259,6 @@ static void idpf_vport_intr_napi_ena_all(struct idpf_= q_vec_rsrc *rsrc) for (u16 q_idx =3D 0; q_idx < rsrc->num_q_vectors; q_idx++) { struct idpf_q_vector *q_vector =3D &rsrc->q_vectors[q_idx]; - idpf_init_dim(q_vector); napi_enable(&q_vector->napi); } } @@ -4581,6 +4601,8 @@ int idpf_vport_intr_alloc(struct idpf_vport *vport, q_coal =3D &user_config->q_coalesce[v_idx]; q_vector->vport =3D vport; + idpf_init_dim(q_vector); + q_vector->tx_itr_value =3D q_coal->tx_coalesce_usecs; q_vector->tx_intr_mode =3D q_coal->tx_intr_mode; q_vector->tx_itr_idx =3D VIRTCHNL2_ITR_IDX_1; -- 2.43.0