linux-kernel - Re: [PATCH v4 07/10] scsi: ufs: Simplify error handling preparation

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Message-ID: <dbe3e867-7e47-e306-038e-2e578845c5ba@acm.org>
Date:   Wed, 23 Jun 2021 14:30:24 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Can Guo <cang@...eaurora.org>, asutoshd@...eaurora.org,
        nguyenb@...eaurora.org, hongwus@...eaurora.org,
        ziqichen@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 07/10] scsi: ufs: Simplify error handling preparation

On 6/23/21 12:35 AM, Can Guo wrote:
> -static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
> +static int ufshcd_err_handling_prepare(struct ufs_hba *hba)
>  {
>  	/*
>  	 * It is not safe to perform error handling while suspend or resume is
>  	 * in progress. Hence the lock_system_sleep() call.
>  	 */
>  	lock_system_sleep();
> +	/*
> +	 * Exclusively call pm_runtime_get_sync(hba->dev) once, in case
> +	 * following ufshcd_rpm_get_sync() fails.
> +	 */
> +	pm_runtime_get_sync(hba->dev);
> +	if (pm_runtime_suspended(hba->dev) || hba->is_sys_suspended) {
> +		pm_runtime_put(hba->dev);
> +		unlock_system_sleep();
> +		return -EINVAL;
> +	}

There is code present in ufshcd_queuecommand() that may trigger data
corruption to prevent that the above pm_runtime_get_sync() call triggers
a deadlock. I think we need a better solution.

Thanks,

Bart.