linux-kernel - Re: [PATCH v3 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling while atomic

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Message-ID: <8b8347dbb9a32c71ba2e6992f30a974c@codeaurora.org>
Date:   Thu, 23 Jan 2020 14:50:16 +0800
From:   hongwus@...eaurora.org
To:     Can Guo <cang@...eaurora.org>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling
 while atomic

Hi Can,

On 2020-01-23 14:12, Can Guo wrote:
> 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.
> 
> Signed-off-by: Can Guo <cang@...eaurora.org>
> ---
>  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 4dfd705..c316a07 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1542,6 +1542,11 @@ 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);

It looks good to me.

Reviewed-by: Hongwu Su <hongwus@...eaurora.org>