Re: [PATCH v5 22/27] scsi: sd: add multipath disk class

On 27/07/2026 16:14, [email protected] wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Empty device release function `sd_mpath_disk_release` violates kobject API rules, masking a future memory leak or Use-After-Free.
> --
> 
> --- Patch [22]: [PATCH v5 22/27] scsi: sd: add multipath disk class ---
> commit f2a48f7b23ab293ee7178e9c9e97a979e61dbc55
> Author: John Garry <[email protected]>
> 
> scsi: sd: add multipath disk class
>      
> This commit adds a new class, sd_mpath_disk_class, which acts as the
> multipath version of the scsi_disk class. It also introduces the
> sd_mpath_disk structure to manage the multipath gendisk.
> 
>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
>> index 599e75f333343..242a15bc2c5bb 100644
>> --- a/drivers/scsi/sd.c
>> +++ b/drivers/scsi/sd.c
> 
> [ ... ]
> 
>> @@ -113,6 +114,39 @@ static mempool_t *sd_page_pool;
>>   static mempool_t *sd_large_page_pool;
>>   static atomic_t sd_large_page_pool_users = ATOMIC_INIT(0);
>>   static struct lock_class_key sd_bio_compl_lkclass;
>> +#ifdef CONFIG_SCSI_MULTIPATH
>> +struct sd_mpath_disk {
>> +	struct scsi_mpath_head		*scsi_mpath_head;
>> +};
>> +
> 
> [Severity: Medium]
> Does this empty release function violate the device lifecycle rules?

it's added later

> 
> The kernel core API strictly forbids empty device release functions (often
> referred to as 'mocking kobjects'). An empty release callback prevents the
> proper freeing of the structure containing the device, which forces the
> memory to either be leaked when the reference count drops to zero, or freed
> synchronously elsewhere leading to a Use-After-Free.
> 
>> +static void sd_mpath_disk_release(struct device *dev)
>> +{
>> +}
>> +
>> +static const struct class sd_mpath_disk_class = {
>> +	.name = "scsi_mpath_disk",
>> +	.dev_release = sd_mpath_disk_release,
>> +};
> 
> [ ... ]
>