On Wed, Jul 03, 2024 at 04:42:21PM +0800, Haoxiang Li wrote:
> child_device_obj->device cannot perform DMA properly if dma_set_mask()
> returns non-zero. Add check for dma_set_mask() and return the error if it
> fails. To do the right cleanup, call dma_set_mask() after device_register()
> so that we can use existent error path of vmbus_device_register().
>
> Fixes: 3a5469582c24 ("Drivers: hv: vmbus: Fix initialization of device object in vmbus_device_register()")
> Signed-off-by: Haoxiang Li <make24@xxxxxxxxxxx>
The email address doesn't seem to match your name. Why?
You should use your own email address to sign off the patches you write.
Thanks,
Wei.
> ---
> Changes in v2:
> Thanks for your comments. They help a lot. It is not sufficient to do the
> cleanup just with kfree(). The memory allocated by dev_set_name()
> should also be freed, which is done by put_device() (finally in
> kobject_cleanup() [1]). I think performing a complete cleanup within
> vmbus_device_register() would be verbose and detrimental to code
> maintenance. I suggest calling dma_set_mask() after device_register(),
> so that proper error handling can be achieved using the existent error path
> of vmbus_device_register(), i.e., err_dev_unregister [2]. Moreover,
> I found a similar usage in dmapool_checks() [3], which calls
> dma_set_mask_and_coherent() after device_register(). I believe the
> modification is workable.
>
> Reference link:
> [1]https://github.com/torvalds/linux/blob/master/lib/kobject.c#L695
> [2]https://github.com/torvalds/linux/blob/master/drivers/hv/vmbus_drv.c#L1933
> [3]https://github.com/torvalds/linux/blob/master/mm/dmapool_test.c#L105
> ---
> drivers/hv/vmbus_drv.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 12a707ab73f8..f3999d8afd77 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1897,7 +1897,6 @@ int vmbus_device_register(struct hv_device *child_device_obj)
>
> child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
> child_device_obj->device.dma_mask = &child_device_obj->dma_mask;
> - dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
>
> /*
> * Register with the LDM. This will kick off the driver/device
> @@ -1910,6 +1909,12 @@ int vmbus_device_register(struct hv_device *child_device_obj)
> return ret;
> }
>
> + ret = dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
> + if (ret) {
> + pr_err("64-bit DMA enable failed!\n");
> + goto err_dev_unregister;
> + }
> +
> child_device_obj->channels_kset = kset_create_and_add("channels",
> NULL, kobj);
> if (!child_device_obj->channels_kset) {
> --
> 2.25.1
>
>
