Re: [PATCH v5 1/7] scsi: ufs: Add "wb_on" sysfs node to control WB on/off

Bean Huo
2020-12-22T20:51:55Z

On Tue, 2020-12-22 at 14:08 +0800, Stanley Chu wrote:
> > + if (kstrtouint(buf, 0, &wb_enable))
> > + return -EINVAL;
> > +
> > + if (wb_enable != 0 && wb_enable != 1)
> > + return -EINVAL;
> > +
> > + pm_runtime_get_sync(hba->dev);
> > + res = ufshcd_wb_ctrl(hba, wb_enable);
>
> May this operation race with UFS shutdown flow?
>
> To be more clear, ufshcd_wb_ctrl() here may be executed after host
> clock
> is disabled by shutdown flow?
>
> If yes, we need to avoid it.
>
> Thanks,
> Stanley Chu

Yes, it is quite possible, but who will mess up this on purpose?

ok, to counterbalance our concerns, I can add checkup:

/* UFS device & link must be active before we change WB status */
if (!ufshcd_is_ufs_dev_active(hba) || !ufshcd_is_link_active(hba))
return -EINVAL;

how do you think about?

Bean