Re: ufs: setting "hba" private pointer too late -- oops in ufshcd_devfreq_get_dev_status()

[Bart Van Assche <bvanassche@xxxxxxx>]

On 11/10/21 6:32 AM, Alexey Dobriyan wrote:
> I've stumbled into a race while working on an earlier kernel,
> but it looks like mainline is affected as well.
>
>          err = ufshcd_init(hba, mmio_base, irq);
> 		async_schedule(ufshcd_async_scan, hba);
> 		ufshcd_add_lus(hba);
> 		if (ufshcd_is_clkscaling_supported(hba)) {
> 			[enable devfreq]
>
>          platform_set_drvdata(pdev, hba);
>
> Device's private pointer is set too late, as devfreq hook get HBA
> pointer from private data and uses it:
>
> 	static int ufshcd_devfreq_get_dev_status(struct device *dev, struct devfreq_dev_status *stat)
> 	{
> 	        struct ufs_hba *hba = dev_get_drvdata(dev);
> 		if (!ufshcd_is_clkscaling_supported(hba))
> 			return -EINVAL;
>
> Unable to handle kernel NULL pointer dereference at virtual address ...0f10
> pc :	ufshcd_devfreq_get_dev_status
> lr :	devfreq_simple_ondemand_func
> 	update_devfreq
> 	devfreq_monitor
>
>
> I reproduced it by turning async LU scan into sync, so it is easier to
> trigger.

Hi Alexey,

Thanks for having reported this. Do you perhaps plan to post a patch to 
fix this?

Thanks,

Bart.