Re: [PATCH v2 5/6] scsi: ufs: Let host_sem cover the entire system suspend/resume

[Bart Van Assche]

On 5/24/21 1:47 AM, 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().

Other SCSI LLDs can perform error handling while system suspend/resume
is in progress. Why can't the UFS driver do this?

Additionally, please document what the purpose of host_sem is before
making any changes to how host_sem is used. The only documentation I
have found of host_sem is the following: "* @host_sem: semaphore used to
serialize concurrent contexts". To me that text is less than useful
since semaphores are almost always used to serialize concurrent code.

Thanks,

Bart.