Thank you for your contribution! Sashiko AI review found 7 potential issue(s) to consider: - [High] pm: Unsafe shared IRQ handling without Runtime PM validation - [High] drm/panthor: CPU soft lockup risk in partition_state_wait() - [Medium] pm: Hardware power leak due to pm_runtime_put_noidle() on teardown paths - [Medium] drm/panthor: OPEN_WINDOW command issued without waiting for hardware reset - [Medium] drm/panthor: TOCTOU race in window_open() and window_close() - [Medium] drm/panthor: Type mismatch passing resource_size_t to %llx format specifier - [Low] drm/panthor: Missing NULL check for devm_kasprintf() string allocation --
commit aae06968ea5bf0c6d7a668bdeb14d91ee2943a9e Author: Karunika Choo <[email protected]> drm/panthor: Add AM_PARTITION_CONTROL support Mali v15 AM GPUs expose AM_PARTITION_CONTROL blocks to manage partition access windows. Add a panthor arbitration platform driver and wire it into Kconfig and the panthor build. > diff --git a/drivers/gpu/drm/panthor/arbitration/panthor_arbitration_drv.c > b/drivers/gpu/drm/panthor/arbitration/panthor_arbitration_drv.c > new file mode 100644 > index 0000000000000..09342245a47d1 > --- /dev/null > +++ b/drivers/gpu/drm/panthor/arbitration/panthor_arbitration_drv.c [ ... ] > +int panthor_arbitration_parse_resource(struct device *dev, > + const struct fwnode_handle *child, > + struct panthor_arbitration_resource *res) > +{ [ ... ] > + if (!fwnode_property_present(child, DT_ID)) { > + dev_warn(dev, "Missing '%s' property in %s@%llx", DT_ID, name, > + res->res.start); > + return -ENODEV; > + } > + > + ret = fwnode_property_read_u32(child, DT_ID, &res->id); > + if (ret) { > + dev_warn(dev, "Malformed '%s' property in %s@%llx", DT_ID, name, > + res->res.start); [Severity: Medium] Will passing res->res.start (a resource_size_t) to a %llx format specifier corrupt the variadic stack arguments on 32-bit builds? [ ... ] > +static int panthor_arbitration_probe(struct platform_device *pdev) > +{ [ ... ] > + ret = panthor_partition_control_init(adev); > + if (ret) > + goto err_term_pc; > + > + ret = of_platform_populate(dev->of_node, NULL, NULL, dev); > + if (ret) > + goto err_depopulate; > + > + pm_runtime_set_autosuspend_delay(dev, PANTHOR_PM_AUTOSUSPEND_DELAY_MS); > + pm_runtime_use_autosuspend(dev); > + > + pm_runtime_put_autosuspend(dev); > + > + return 0; > + > +err_depopulate: > + of_platform_depopulate(dev); > + > +err_term_pc: > + panthor_partition_control_term(adev); > + pm_runtime_put_noidle(dev); > + return ret; [Severity: Medium] Does using pm_runtime_put_noidle() here leave the hardware permanently powered on during a probe failure? Since devres cleanup will invoke pm_runtime_disable() and cancel any pending PM operations, using put_noidle instead of put_sync_suspend() drops the usage count but doesn't schedule an idle check. [ ... ] > diff --git a/drivers/gpu/drm/panthor/arbitration/panthor_partition_control.c > b/drivers/gpu/drm/panthor/arbitration/panthor_partition_control.c > new file mode 100644 > index 0000000000000..e6fbf5e58b51a > --- /dev/null > +++ b/drivers/gpu/drm/panthor/arbitration/panthor_partition_control.c [ ... ] > +static int partition_state_wait(struct panthor_partition_control *pc, u32 > state) > +{ > + u32 partition_state; > + > + return read_poll_timeout_atomic(partition_state_get, partition_state, > + partition_state == state, > + PART_REG_POLL_SLEEP_US, > + PART_STATE_TRANSITION_TIMEOUT_US, > + false, pc); > +} [Severity: High] Can read_poll_timeout_atomic() trigger CPU soft lockups if it busy-waits for up to 5 seconds? The PART_STATE_TRANSITION_TIMEOUT_US macro is set to 5,000,000 (5 seconds). The atomic variant disables preemption and uses udelay(). Since callers run in a sleepable context, should this use read_poll_timeout() instead? [ ... ] > +static int window_close(struct panthor_partition_control *pc) > +{ > + /* Partition already closed. */ > + if (partition_state_get(pc) == PART_STATE_RESET) > + return 1; > + > + guard(spinlock_irqsave)(&pc->lock); [Severity: Medium] Is there a time-of-check to time-of-use (TOCTOU) race here since the hardware state is checked before the pc->lock is acquired? [ ... ] > +static int window_open(struct panthor_partition_control *pc, u8 aw_id) > +{ > + if (aw_id >= AM_ARB_MAX_AW_COUNT) > + return -EINVAL; > + > + if (partition_state_get(pc) == PART_STATE_WINDOW_OPEN) { > + u8 cur_aw = partition_aw_get(pc); > + > + if (cur_aw == aw_id) > + return 0; > + > + dev_warn(pc->dev, > + "%s: OPEN_WINDOW(%u): Already opened for aw=%u, > state=%u. Closing...", > + pc->name, aw_id, cur_aw, partition_state_get(pc)); > + > + window_close(pc); > + } > + > + guard(spinlock_irqsave)(&pc->lock); [Severity: Medium] Similar to window_close(), we check the hardware state locklessly before acquiring pc->lock. Can concurrent calls observe the state incorrectly? > + > + gpu_write(pc->iomem, AM_PART_COMMAND, > + AM_PART_SET_COMMAND(PART_CMD_OPEN_WINDOW) | > AM_PART_SET_WINDOW(aw_id)); [Severity: Medium] Does window_close() ensure the hardware has reached PART_STATE_RESET before we issue the OPEN_WINDOW command here? If window_close() asynchronously processes the close command, sending an open command immediately to the exact same register might create a race condition, potentially causing a PART_INVALID_COMMAND fault. [ ... ] > +static irqreturn_t partition_irq_raw_handler(int irq, void *data) > +{ > + struct panthor_partition_control *pc = data; > + u32 status; > + > + status = gpu_read(pc->iomem, AM_PART_IRQ_STATUS); > + if (!status) > + return IRQ_NONE; [Severity: High] Since this handler is registered with IRQF_SHARED, could reading from the hardware register without Runtime PM validation cause issues? Other devices on the same interrupt line can trigger this handler. If the device is runtime-suspended, this unconditional read could result in a bus fault or return garbage data. Should this use pm_runtime_get_if_active() first? [ ... ] > +static int partition_control_init(struct panthor_arbitration *adev, > + const struct fwnode_handle *child) > +{ [ ... ] > + pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL); > + if (!pc) > + return -ENOMEM; > + > + name = devm_kasprintf(dev, GFP_KERNEL, "pc%d", res.id); > + > + iomem = devm_ioremap_resource(dev, &res.res); [Severity: Low] Is there a missing NULL check for the name allocation here? If devm_kasprintf() fails, name will be NULL, which is later passed to another devm_kasprintf() for the IRQ name. [ ... ] > + irqdata = irq_get_irq_data(irq); > + if (irqdata) > + irq_flags = irqd_get_trigger_type(irqdata); > + > + ret = devm_request_irq( > + dev, irq, partition_irq_raw_handler, irq_flags | IRQF_SHARED, > + devm_kasprintf(dev, GFP_KERNEL, "panthor-%s-irq", name), pc); > + if (ret) > + return ret; [Severity: High] The irq is requested here, but it doesn't seem to be saved into pc->irq. Without storing it, panthor_partition_control_suspend() cannot call synchronize_irq() during power down, which risks suspending the hardware while an interrupt is mid-flight. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=13
