2020-05-25 21:55:21

by Jeffrey Hugo

Subject: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

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().

Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers")
Signed-off-by: Jeffrey Hugo <[email protected]>
---
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);
}

/**
--
2.17.1

2020-05-26 06:28:27

by Avri Altman

Subject: RE: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

> 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().
>
> Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers")
> Signed-off-by: Jeffrey Hugo <[email protected]>
Reviewed-by: Avri Altman <[email protected]>

2020-05-26 09:44:16

by Bean Huo

Subject: Re: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

On Tue, 2020-05-26 at 06:25 +0000, Avri Altman wrote:
>
> > 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().
> >
> > Fixes: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus
> > registers")
> > Signed-off-by: Jeffrey Hugo <[email protected]>
>
> Reviewed-by: Avri Altman <[email protected]>
Reviewed-by: Bean Huo <[email protected]>

2020-05-27 05:06:09

by Martin K. Petersen

Subject: Re: [PATCH] scsi: ufs-qcom: Fix scheduling while atomic issue

On Mon, 25 May 2020 13:41:25 -0700, Jeffrey Hugo wrote:

> 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
>
> [...]

Applied to 5.8/scsi-queue, thanks!

[1/1] scsi: ufs-qcom: Fix scheduling while atomic issue
https://git.kernel.org/mkp/scsi/c/3be60b564de4

--
Martin K. Petersen Oracle Linux Engineering