Re: [PATCH 0/2] Fix debugfs register access while suspended

[Niklas Söderlund]

Hi Geert,

Thanks for your series.

On 2020-01-24 14:29:55 +0100, Geert Uytterhoeven wrote:
> 	Hi all,
> 
> While comparing register values read from debugfs files under
> /sys/kernel/debug/ccree/, I noticed some oddities.
> Apparently there is no guarantee these registers are read from the
> device while it is resumed.  This may lead to bogus values, or crashes
> and lock-ups.
> 
> This patch series:
>   1. Allows debugfs_create_regset32() to be used for devices whose
>      registers must be accessed when resumed,
>   2. Fixes the CCREE driver to make use of this.
> 
> I have identified several other drivers that may be affected (i.e.
> using debugfs_create_regset32() and pm_runtime_*()):
>   - drivers/gpu/drm/msm/disp/dpu1
>   - drivers/usb/dwc3
>   - drivers/usb/host/ehci-omap.c
>   - drivers/usb/host/ehci-tegra.c
>   - drivers/usb/host/ohci-platform.c
>   - drivers/usb/host/xhci.c
>   - drivers/usb/host/xhci-dbgcap.c
>   - drivers/usb/host/xhci-histb.c
>   - drivers/usb/host/xhci-hub.c
>   - drivers/usb/host/xhci-mtk.c
>   - drivers/usb/host/xhci-pci.c
>   - drivers/usb/host/xhci-plat.c
>   - drivers/usb/host/xhci-tegra.c
>   - drivers/usb/mtu3
>   - drivers/usb/musb
> 
> Some of these call pm_runtime_forbid(), but given the comment "users
> should enable runtime pm using power/control in sysfs", this can be
> overridden from userspace, so these are unsafe, too?
> 
> Thanks for your comments!

Looks good to me,

Reviewed-by: Niklas Söderlund <niklas.soderlund@xxxxxxxxxxxx>

> 
> Geert Uytterhoeven (2):
>   debugfs: regset32: Add Runtime PM support
>   crypto: ccree - fix debugfs register access while suspended
> 
>  drivers/crypto/ccree/cc_debugfs.c | 2 ++
>  fs/debugfs/file.c                 | 8 ++++++++
>  include/linux/debugfs.h           | 1 +
>  3 files changed, 11 insertions(+)
> 
> -- 
> 2.17.1
> 
> Gr{oetje,eeting}s,
> 
> 						Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> 							    -- Linus Torvalds

-- 
Regards,
Niklas Söderlund