linux-kernel - Re: [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset and restore path

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Message-ID: <CAGOxZ502wp17UFEk67Qno9DQ0dFPfwMRTLNTCvOXibQDhOw4SA@mail.gmail.com>
Date:   Wed, 13 Nov 2019 07:54:28 +0530
From:   Alim Akhtar <alim.akhtar@...il.com>
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>,
        Bean Huo <beanhuo@...ron.com>,
        Subhash Jadavani <subhashj@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset
 and restore path

Hi Can,

On Fri, Nov 8, 2019 at 1:50 PM Can Guo <cang@...eaurora.org> wrote:
>
> In UFS host reset and restore path, before probe, we stop and start the
> host controller once. After host controller is stopped, the pending
> requests, if any, are cleared from the doorbell, but no completion IRQ
> would be raised due to the hba is stopped.
> These pending requests shall be completed along with the first NOP_OUT
> command(as it is the first command which can raise a transfer completion
> IRQ) sent during probe.
> Since the OCSs of these pending requests are not SUCCESS(because they are
> not yet literally finished), their UPIUs shall be dumped. When there are
> multiple pending requests, the UPIU dump can be overwhelming and may lead
> to stability issues because it is in atomic context.
> Therefore, before probe, complete these pending requests right after host
> controller is stopped.
>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> ---
Looks good, I hope this is tested on your platform.
Reviewed-by: Alim Akhtar <alim.akhtar@...sung.com>

>  drivers/scsi/ufs/ufshcd.c | 20 +++++++-------------
>  1 file changed, 7 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 5950a7c..4df4136 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5404,8 +5404,8 @@ static void ufshcd_err_handler(struct work_struct *work)
>
>         /*
>          * if host reset is required then skip clearing the pending
> -        * transfers forcefully because they will automatically get
> -        * cleared after link startup.
> +        * transfers forcefully because they will get cleared during
> +        * host reset and restore
>          */
>         if (needs_reset)
>                 goto skip_pending_xfer_clear;
> @@ -6333,9 +6333,13 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
>         int err;
>         unsigned long flags;
>
> -       /* Reset the host controller */
> +       /*
> +        * Stop the host controller and complete the requests
> +        * cleared by h/w
> +        */
>         spin_lock_irqsave(hba->host->host_lock, flags);
>         ufshcd_hba_stop(hba, false);
> +       ufshcd_complete_requests(hba);
>         spin_unlock_irqrestore(hba->host->host_lock, flags);
>
>         /* scale up clocks to max frequency before full reinitialization */
> @@ -6369,7 +6373,6 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
>  static int ufshcd_reset_and_restore(struct ufs_hba *hba)
>  {
>         int err = 0;
> -       unsigned long flags;
>         int retries = MAX_HOST_RESET_RETRIES;
>
>         do {
> @@ -6379,15 +6382,6 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba)
>                 err = ufshcd_host_reset_and_restore(hba);
>         } while (err && --retries);
>
> -       /*
> -        * After reset the door-bell might be cleared, complete
> -        * outstanding requests in s/w here.
> -        */
> -       spin_lock_irqsave(hba->host->host_lock, flags);
> -       ufshcd_transfer_req_compl(hba);
> -       ufshcd_tmc_handler(hba);
> -       spin_unlock_irqrestore(hba->host->host_lock, flags);
> -
>         return err;
>  }
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>


-- 
Regards,
Alim