Re: [PATCH] usb: typec: ucsi: acpi: Remove notifier before destroying handler

Mark Pearson
2023-03-24T12:50:45Z

Hi Heikki,

On Thu, Mar 23, 2023, at 5:57 AM, Heikki Krogerus wrote:
> On Tue, Mar 21, 2023 at 03:01:36PM -0400, Mark Pearson wrote:
>> Was debugging another issue (since fixed) and noticed that the acpi
>> notify_handler should be removed before the ucsi object is destroyed.
>>
>> This isn't fixing any issues that I'm aware of - but I assume could
>> potentially lead to a race condition if you were really unlucky?
>>
>> Signed-off-by: Mark Pearson <mpearson-lenovo@squebb.ca>
>> ---
>> drivers/usb/typec/ucsi/ucsi_acpi.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/typec/ucsi/ucsi_acpi.c b/drivers/usb/typec/ucsi/ucsi_acpi.c
>> index ce0c8ef80c04..be3bf4f996d3 100644
>> --- a/drivers/usb/typec/ucsi/ucsi_acpi.c
>> +++ b/drivers/usb/typec/ucsi/ucsi_acpi.c
>> @@ -176,12 +176,12 @@ static int ucsi_acpi_remove(struct platform_device *pdev)
>> {
>> struct ucsi_acpi *ua = platform_get_drvdata(pdev);
>>
>> - ucsi_unregister(ua->ucsi);
>> - ucsi_destroy(ua->ucsi);
>> -
>> acpi_remove_notify_handler(ACPI_HANDLE(&pdev->dev), ACPI_DEVICE_NOTIFY,
>> ucsi_acpi_notify);
>>
>> + ucsi_unregister(ua->ucsi);
>> + ucsi_destroy(ua->ucsi);
>> +
>> return 0;
>> }
>
> Calling ucsi_desctroy() after removing the notifier makes sense to me,
> but do you also need to unregister the instance after that?
>
> You may still be in the middle of init or resume, so I think we need
> to accept notifications until we are sure those have finished, i.e.
> ucsi_unregister() has finished.
>

That makes sense - I hadn't considered that.
I'll post an updated patch with the acpi_remove_notify_handler between the two calls.

Thanks for the review
Mark