Re: [PATCH v1 5/6] scsi: ufs: Let host_sem cover the entire system suspend/resume

[Can Guo]

Hi Bart,

On 2021-05-14 11:55, Bart Van Assche wrote:
> On 5/12/21 10:55 PM, Can Guo wrote:
> > UFS error handling now is doing more than just re-probing, but also 
> > sending
> > scsi cmds, e.g., for clearing UACs, and recovering runtime PM error, 
> > which
> > may change runtime status of scsi devices. To protect system 
> > suspend/resume
> > from being disturbed by error handling, move the host_sem from wl pm 
> > ops
> > to ufshcd_suspend_prepare() and ufshcd_resume_complete().
>
> In ufshcd.h I found the following:
>
>  * @host_sem: semaphore used to serialize concurrent contexts
>
> That's the wrong way to use a synchronization object. A synchronization
> object must protect data instead of code. Does host_sem perhaps need to
> be split into multiple synchronization objects?

Thanks for the comments. These contexts are changing critical data and
registers, so the sem is used to protect data actually, just like the
scaling_lock protecting scaling and cmd transations.

Thanks,

Can Guo.

> Thanks,
>
> Bart.