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Sashiko AI review found 3 potential issue(s) to consider: > > New issues: > - [High] The split IRQ handlers break the FLEXCAN_QUIRK_BROKEN_PERR_STATE workaround on multi-IRQ platforms. Please check this one, You can fix pre-existing issue later. Frank > > Pre-existing issues: > - [Critical] Concurrent execution of split IRQ handlers locklessly corrupts the shared `skb_irq_queue`. > - [High] The patch fails to fix duplicate frame processing for platforms with multiple mailbox IRQs. > -- > > --- Patch [1]: [RESEND PATCH v6 1/6] can: flexcan: use dedicated IRQ handlers for multi-IRQ platforms --- > commit 4696683063946bcc95216f931b7fa509b55610f8 > Author: Ciprian Marian Costea > Date: Fri Aug 14 09:03:18 2026 +0000 > > can: flexcan: use dedicated IRQ handlers for multi-IRQ platforms > > This commit splits the monolithic flexcan IRQ handler into dedicated > handlers for mailbox, bus error, and state change events. This is intended > to prevent duplicate frame processing on multi-IRQ platforms where distinct > IRQ lines can dispatch concurrently. > > > diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c > > index f5d22c61503fa..f73ff442d5304 100644 > > --- a/drivers/net/can/flexcan/flexcan-core.c > > +++ b/drivers/net/can/flexcan/flexcan-core.c > [ ... ] > > @@ -1131,25 +1129,57 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id) > > netif_wake_queue(dev); > > } > > > > + return handled; > > +} > > + > > +/* Process bus error events */ > > +static irqreturn_t flexcan_do_berr(struct net_device *dev) > > +{ > > + struct flexcan_priv *priv = netdev_priv(dev); > > + struct flexcan_regs __iomem *regs = priv->regs; > > + irqreturn_t handled = IRQ_NONE; > > + u32 reg_esr; > > + > > reg_esr = priv->read(®s->esr); > > > > - /* ACK all bus error, state change and wake IRQ sources */ > > - if (reg_esr & (FLEXCAN_ESR_ALL_INT | FLEXCAN_ESR_WAK_INT)) { > > + /* ACK bus error interrupt source */ > > + if (reg_esr & FLEXCAN_ESR_ERR_INT) { > > handled = IRQ_HANDLED; > > - priv->write(reg_esr & (FLEXCAN_ESR_ALL_INT | FLEXCAN_ESR_WAK_INT), ®s->esr); > > + priv->write(FLEXCAN_ESR_ERR_INT, ®s->esr); > > } > > > > - /* state change interrupt or broken error state quirk fix is enabled */ > > - if ((reg_esr & FLEXCAN_ESR_ERR_STATE) || > > - (priv->devtype_data.quirks & (FLEXCAN_QUIRK_BROKEN_WERR_STATE | > > - FLEXCAN_QUIRK_BROKEN_PERR_STATE))) > > - flexcan_irq_state(dev, reg_esr); > > - > > /* bus error IRQ - handle if bus error reporting is activated */ > > if ((reg_esr & FLEXCAN_ESR_ERR_BUS) && > > (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) > > flexcan_irq_bus_err(dev, reg_esr); > > > > + return handled; > > +} > > [Severity: High] > Does this break the FLEXCAN_QUIRK_BROKEN_PERR_STATE workaround? > > Before this patch, the monolithic flexcan_irq() checked this quirk and called > flexcan_irq_state() on any interrupt. > > The FLEXCAN_QUIRK_BROKEN_PERR_STATE workaround relies on enabling the bus error > interrupt to catch state changes on platforms where the state interrupt is > broken. > > Now that the bus error interrupt is routed exclusively to flexcan_do_berr(), > which never invokes flexcan_irq_state(), won't state transitions (like bus > warning or bus-off) be silently ignored on affected platforms? > > [ ... ] > > +/* Mailbox IRQ handler for multi-IRQ platforms */ > > +static irqreturn_t flexcan_irq_mb(int irq, void *dev_id) > > +{ > > + struct net_device *dev = dev_id; > > + struct flexcan_priv *priv = netdev_priv(dev); > > + irqreturn_t handled; > > + > > + handled = flexcan_do_mb(dev); > > [Severity: High] > This is a pre-existing issue, but does this still allow duplicate frame > processing? > > If a platform has a secondary mailbox IRQ (FLEXCAN_QUIRK_SECONDARY_MB_IRQ), > flexcan_open() registers flexcan_irq_mb() for the secondary IRQ, and the > primary IRQ registers either flexcan_irq() or flexcan_irq_mb(). > > Because these can run concurrently on different CPUs, and flexcan_do_mb() > unconditionally processes all active mailboxes globally, won't both threads > still race and process the same frames? > > > + > > + if (handled) > > + can_rx_offload_irq_finish(&priv->offload); > > [Severity: Critical] > This is a pre-existing issue, but does splitting the IRQ handlers make > skb_irq_queue vulnerable to lockless corruption? > > When flexcan_irq_mb(), flexcan_irq_boff(), and flexcan_irq_berr() run > concurrently on different CPUs, they can independently call the can_rx_offload > API (like can_rx_offload_irq_offload_timestamp() and > can_rx_offload_queue_timestamp()). > > These functions insert SKBs into offload->skb_irq_queue using the lockless > __skb_queue_add_sort(). > > Additionally, they concurrently call can_rx_offload_irq_finish(), which > splices the list locklessly: > > drivers/net/can/dev/rx-offload.c:can_rx_offload_irq_finish() { > ... > spin_lock_irqsave(&offload->skb_queue.lock, flags); > skb_queue_splice_tail_init(&offload->skb_irq_queue, &offload->skb_queue); > spin_unlock_irqrestore(&offload->skb_queue.lock, flags); > ... > } > > Will this concurrent lockless access corrupt the skb->next / skb->prev pointers > leading to a kernel panic? > > > + > > + return handled; > > +} > > -- > Sashiko AI review · https://sashiko.dev/#/patchset/20260814090324.647898-1-ciprianmarian.costea@oss.nxp.com?part=1