Re: [v6,2/7] ptp: vmclock: support device notifications
From: Jakub Kicinski <kuba@kernel.org>
Date: 2026-01-23 03:11:48
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This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- ptp: vmclock: support device notifications This patch adds optional device notification support to VMClock, allowing the hypervisor to notify the driver when seq_count changes. It also adds poll() support to propagate these notifications to userspace.
quoted hunk ↗ jump to hunk
diff --git a/drivers/ptp/ptp_vmclock.c b/drivers/ptp/ptp_vmclock.c index b3a83b03d9c1..38b2bacb755e 100644 --- a/drivers/ptp/ptp_vmclock.c +++ b/drivers/ptp/ptp_vmclock.c
[ ... ]
+static void
+vmclock_acpi_notification_handler(acpi_handle __always_unused handle,
+ u32 __always_unused event, void *dev)
+{
+ struct device *device = dev;
+ struct vmclock_state *st = device->driver_data;
+
+ wake_up_interruptible(&st->disrupt_wait);
+}
+
+static int vmclock_setup_notification(struct device *dev, struct vmclock_state *st)
+{[ ... ]
+ status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY, + vmclock_acpi_notification_handler, + dev);
Since acpi_install_notify_handler() is called here, should there be a corresponding acpi_remove_notify_handler() in vmclock_remove()? Currently the handler remains registered after device removal, which could lead to a use-after-free if the hypervisor sends a notification after the driver state has been freed. [ ... ]
quoted hunk ↗ jump to hunk
@@ -549,6 +653,11 @@ static int vmclock_probe(struct platform_device *pdev) if (ret) return ret; + init_waitqueue_head(&st->disrupt_wait); + ret = vmclock_setup_notification(dev, st); + if (ret) + return ret;
[ ... ]
quoted hunk ↗ jump to hunk
@@ -581,6 +690,8 @@ static int vmclock_probe(struct platform_device *pdev) return -ENODEV; } + dev->driver_data = st;
Is there a race window here? The ACPI notification handler is installed in vmclock_setup_notification() which runs earlier in vmclock_probe(), but the handler accesses device->driver_data. If the hypervisor sends a notification between vmclock_setup_notification() and this assignment, vmclock_acpi_notification_handler() would dereference NULL or garbage. I see this is fixed later in the series by commit 47fdd294385e which moves dev->driver_data = st before vmclock_setup_notification(). -- pw-bot: cr