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Subject: Re: [PATCH v4 5/8] scsi: ufs: Fix ufshcd_hold() caused scheduling
 while atomic
To:     Can Guo <cang@codeaurora.org>, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, rnayak@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        saravanak@google.com, salyzyn@google.com
Cc:     Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        Pedro Sousa <pedrom.sousa@synopsys.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Venkat Gopalakrishnan <venkatg@codeaurora.org>,
        Tomas Winkler <tomas.winkler@intel.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1579764349-15578-1-git-send-email-cang@codeaurora.org>
 <1579764349-15578-6-git-send-email-cang@codeaurora.org>
From:   "Asutosh Das (asd)" <asutoshd@codeaurora.org>
Message-ID: <4aaf60bc-b398-67a1-7ed5-e0571f30bc95@codeaurora.org>
Date:   Fri, 24 Jan 2020 10:07:23 -0800
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On 1/22/2020 11:25 PM, 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@codeaurora.org>
> Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
> ---

Reviewed-by: Asutosh Das <asutoshd@codeaurora.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);
> 


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