Re: [PATCH] dmaengine: switchtec-dma: Fix device reference leak in switchtec_dma_create()

[Logan Gunthorpe]

On 2026-09-16 10:05, Frank Li wrote:
> On Wed, Sep 16, 2026 at 09:33:32AM +0000, Wentao Liang wrote:
>> switchtec_dma_create() takes a reference on the PCI device with
>> get_device() and stores it in dma->dev. The reference is normally
>> dropped by switchtec_dma_release(), the device_release() callback,
>> which only runs after a successful dma_async_device_register(). If
>> the registration fails, the code frees the dma device directly from
>> the err_chans_release_exit label without ever dropping that extra
>> reference, leaking the reference taken on the PCI device.
>>
>> Drop the reference with put_device() on the error path.
>>
>> Fixes: d9587042b50f ("dmaengine: switchtec-dma: Introduce Switchtec DMA engine skeleton")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Wentao Liang <vulab@xxxxxxxxxxx>
>> ---
>>  drivers/dma/switchtec_dma.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/dma/switchtec_dma.c b/drivers/dma/switchtec_dma.c
>> index 3ef928640615..b07bdd0ac540 100644
>> --- a/drivers/dma/switchtec_dma.c
>> +++ b/drivers/dma/switchtec_dma.c
>> @@ -1297,6 +1297,7 @@ static int switchtec_dma_create(struct pci_dev *pdev)
>>
>>  err_chans_release_exit:
>>  	switchtec_dma_chans_release(pdev, swdma_dev);
>> +	put_device(dma->dev);
> 
> Does switchtec_dma_remove() also need put_device()?

No, the release already happens in switchtec_dma_release() after the
device is removed. It can't be done in swtichtec_dma_remove() or it will
be potentially used if the device still exists after
switchtec_dma_remove() completes.

The patch looks correct to me but it will conflict with the patches in
my series waiting for merging:

https://lore.kernel.org/all/20260902062153.31048-1-logang@xxxxxxxxxxxx/T/#u

I'd appreciate it if my series could go in first and this gets rebased
on top of it.

Other than that:

Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>

Thanks!

Logan