From: Haoxiang Li <[email protected]> Sent: Sunday, June 30, 2024 7:31 PM > > 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. child_device_obj->device is not initialized here, so use kfree() to > free child_device_obj->device. > > Fixes: 3a5469582c24 ("Drivers: hv: vmbus: Fix initialization of device object > in > vmbus_device_register()") > Signed-off-by: Haoxiang Li <[email protected]> > --- > drivers/hv/vmbus_drv.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 12a707ab73f8..daa584eaa2af 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -1897,7 +1897,13 @@ 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)); > + ret = dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64)); > + > + if (ret) { > + pr_err("64-bit DMA enable failed\n"); > + kfree(&child_device_obj->device); > + return ret; > + }
I commented on a previous attempt to check the return value from dma_set_mask(). See [1]. See also commit f92a4b50f0bd that adds some detail about the error handling in vmbus_device_register(). It's all rather messy. I have not personally worked through the details, so I'm not sure of what the right cleanup is. But I don't think it is sufficient to just do the kfree() as your patch proposes. Or if I'm wrong, and that *is* sufficient, please provides details on the reasoning why, and let's make sure to record that for future reference! :-) Michael [1] https://lore.kernel.org/linux-hyperv/[email protected]/
