linux-kernel - RE: [PATCH v6 3/8] scsi: ufs-qcom: Fix schedule while atomic error in ufs_qcom_dump_dbg

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Date:   Mon, 27 Jul 2020 13:05:47 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Can Guo <cang@...eaurora.org>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "nguyenb@...eaurora.org" <nguyenb@...eaurora.org>,
        "hongwus@...eaurora.org" <hongwus@...eaurora.org>,
        "rnayak@...eaurora.org" <rnayak@...eaurora.org>,
        "sh425.lee@...sung.com" <sh425.lee@...sung.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        "saravanak@...gle.com" <saravanak@...gle.com>,
        "salyzyn@...gle.com" <salyzyn@...gle.com>
CC:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v6 3/8] scsi: ufs-qcom: Fix schedule while atomic error in
 ufs_qcom_dump_dbg_regs

> Dumping testbus registers needs to sleep a bit intermittently as there are
> too many of them. Skip them for those contexts where sleep is not allowed.
> 
> Signed-off-by: Can Guo <cang@...eaurora.org>
> ---
>  drivers/scsi/ufs/ufs-qcom.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 7da27ee..7831b2b 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -1651,13 +1651,16 @@ static void ufs_qcom_dump_dbg_regs(struct
> ufs_hba *hba)
>         ufshcd_dump_regs(hba, REG_UFS_SYS1CLK_1US, 16 * 4,
>                          "HCI Vendor Specific Registers ");
> 
> -       /* sleep a bit intermittently as we are dumping too much data */
>         ufs_qcom_print_hw_debug_reg_all(hba, NULL,
> ufs_qcom_dump_regs_wrapper);
> -       udelay(1000);
> -       ufs_qcom_testbus_read(hba);
> -       udelay(1000);
> -       ufs_qcom_print_unipro_testbus(hba);
> -       udelay(1000);
> +
> +       if (in_task()) {
> +               /* sleep a bit intermittently as we are dumping too much data */
> +               usleep_range(1000, 1100);
> +               ufs_qcom_testbus_read(hba);
> +               usleep_range(1000, 1100);
> +               ufs_qcom_print_unipro_testbus(hba);
> +               usleep_range(1000, 1100);
> +       }
>  }
How about moving the intermittent sleep out of the check if preemption is disabled?
And maybe then you need to switch back to uedlay?