[PATCH v2] drm/xe/i2c: cancel the client work on remove

[Fan Wu]

xe_i2c_notifier() stores the DesignWare adapter in i2c->adapter and
schedules i2c->work when the adapter is registered under the xe I2C
platform device, and xe_i2c_client_work() then instantiates the AMC
client device on that adapter.

xe_i2c_remove() tears down the AMC, unregisters the client devices,
the bus notifier and the adapter platform device, but it never drains
i2c->work. A work item that is still queued or running when the
adapter is unregistered dereferences i2c->adapter in
i2c_new_client_device() after platform_device_unregister() has
released the adapter. The work item is also embedded in the
devm-allocated struct xe_i2c, so a work item still queued after the
drm device devm unwind frees that allocation runs its callback on
freed memory.

Cancel the work in xe_i2c_remove(), after bus_unregister_notifier()
so that no new instance can be scheduled, and before the adapter is
unregistered so that a running instance still finds a live adapter.

This issue was found by an in-house static analysis tool.

Fixes: f0e53aadd702 ("drm/xe: Support for I2C attached MCUs")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: Codex:gpt-5.6
Co-developed-by: Song Li <songl@xxxxxxxxxx>
Signed-off-by: Song Li <songl@xxxxxxxxxx>
Signed-off-by: Fan Wu <fanwu01@xxxxxxxxxx>
---

Changes in v2:
- Rebase onto drm-xe-next as requested. xe_i2c_remove() now calls
  xe_amc_exit() first and no longer tears down an irqdomain. The bus
  notifier still needs to be unregistered before draining i2c->work,
  so keep cancel_work_sync() at that point. (Rodrigo Vivi)

Link: https://lore.kernel.org/r/20260909052328.654682-1-fanwu01@xxxxxxxxxx
 drivers/gpu/drm/xe/xe_i2c.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/xe/xe_i2c.c b/drivers/gpu/drm/xe/xe_i2c.c
index d8fa68206f41..143ca7145e4f 100644
--- a/drivers/gpu/drm/xe/xe_i2c.c
+++ b/drivers/gpu/drm/xe/xe_i2c.c
@@ -334,6 +334,7 @@ static void xe_i2c_remove(void *data)
 	}
 
 	bus_unregister_notifier(&i2c_bus_type, &i2c->bus_notifier);
+	cancel_work_sync(&i2c->work);
 	xe_i2c_unregister_adapter(i2c);
 }