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    Subject[PATCH AUTOSEL 5.7 283/388] scsi: ufs-qcom: Fix scheduling while atomic issue
    Date
    From: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>

    [ Upstream commit 3be60b564de49875e47974c37fabced893cd0931 ]

    ufs_qcom_dump_dbg_regs() uses usleep_range, a sleeping function, but can be
    called from atomic context in the following flow:

    ufshcd_intr -> ufshcd_sl_intr -> ufshcd_check_errors ->
    ufshcd_print_host_regs -> ufshcd_vops_dbg_register_dump ->
    ufs_qcom_dump_dbg_regs

    This causes a boot crash on the Lenovo Miix 630 when the interrupt is
    handled on the idle thread.

    Fix the issue by switching to udelay().

    Link: https://lore.kernel.org/r/20200525204125.46171-1-jeffrey.l.hugo@gmail.com
    Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers")
    Reviewed-by: Bean Huo <beanhuo@micron.com>
    Reviewed-by: Avri Altman <avri.altman@wdc.com>
    Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/scsi/ufs/ufs-qcom.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
    index 19aa5c44e0da..f938867301a0 100644
    --- a/drivers/scsi/ufs/ufs-qcom.c
    +++ b/drivers/scsi/ufs/ufs-qcom.c
    @@ -1658,11 +1658,11 @@ static void ufs_qcom_dump_dbg_regs(struct ufs_hba *hba)

    /* 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);
    - usleep_range(1000, 1100);
    + udelay(1000);
    ufs_qcom_testbus_read(hba);
    - usleep_range(1000, 1100);
    + udelay(1000);
    ufs_qcom_print_unipro_testbus(hba);
    - usleep_range(1000, 1100);
    + udelay(1000);
    }

    /**
    --
    2.25.1
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