RE: [PATCH v7 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling while atomic

[Avri Altman]

Hi,

> 
> The async version of ufshcd_hold(async == true), which is only called
> in queuecommand path as for now, is expected to work in atomic context,
> thus it should not sleep or schedule out. When it runs into the condition
> that clocks are ON but link is still in hibern8 state, it should bail out
> without flushing the clock ungate work.

Fixes: f2a785ac2312 (scsi: ufshcd: Fix race between clk scaling and ungate work)
> 
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> Reviewed-by: Hongwu Su <hongwus@xxxxxxxxxxxxxx>
> Reviewed-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
> Reviewed-by: Bean Huo <beanhuo@xxxxxxxxxx>
> Reviewed-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
> ---
>  drivers/scsi/ufs/ufshcd.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index bbc2607..e8f7f9d 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1518,6 +1518,11 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
>                  */
>                 if (ufshcd_can_hibern8_during_gating(hba) &&
>                     ufshcd_is_link_hibern8(hba)) {
> +                       if (async) {
> +                               rc = -EAGAIN;
> +                               hba->clk_gating.active_reqs--;
> +                               break;
> +                       }
>                         spin_unlock_irqrestore(hba->host->host_lock, flags);
>                         flush_work(&hba->clk_gating.ungate_work);
>                         spin_lock_irqsave(hba->host->host_lock, flags);
Since now the above code is shared in all cases,
Maybe find a more economical way to pack it?

Thanks,
Avri


> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> Forum,
> a Linux Foundation Collaborative Project