linux-kernel - Re: [PATCH v2] staging: rtl8192u: Fix sleep in atomic context bug in dm_fsync_timer

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Date:   Sat, 25 Jun 2022 11:30:13 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     duoming@....edu.cn
Cc:     linux-staging@...ts.linux.dev, davem@...emloft.net,
        alexander.deucher@....com, kuba@...nel.org, broonie@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: rtl8192u: Fix sleep in atomic context bug in
 dm_fsync_timer_callback

On Sat, Jun 25, 2022 at 05:21:06PM +0800, duoming@....edu.cn wrote:
> Hello,
> 
> > > On Thu, Jun 23, 2022 at 01:59:12PM +0800, Duoming Zhou wrote:
> > > > There are sleep in atomic context bugs when dm_fsync_timer_callback is
> > > > executing. The root cause is that the memory allocation functions with
> > > > GFP_KERNEL or GFP_NOIO parameters are called in dm_fsync_timer_callback
> > > > which is a timer handler. The call paths that could trigger bugs are
> > > > shown below:
> > > > 
> > > >     (interrupt context)
> > > > dm_fsync_timer_callback
> > > >   write_nic_byte
> > > >     kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> > > >     usb_control_msg
> > > >       kmalloc(.., GFP_NOIO); //may sleep
> > > >   write_nic_dword
> > > >     kzalloc(sizeof(data), GFP_KERNEL); //may sleep
> > > >     usb_control_msg
> > > >       kmalloc(.., GFP_NOIO); //may sleep
> > > > 
> > > > This patch uses delayed work to replace timer and moves the operations
> > > > that may sleep into the delayed work in order to mitigate bugs.
> > > > 
> > > > Fixes: 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging")
> > > > Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> > > > ---
> > > > Changes in v2:
> > > >   - Use delayed work to replace timer.
> > > 
> > > Did you test this with real hardware to verify it still works?
> > 
> > I am testing this and I will give you feedback within one or two days.
> 
> Do you know what vendor id and device id use the r8192u_usb driver?

The vendor/device ids are in the driver itself.  Also in the output of
modinfo:
	❯ modinfo drivers/staging/rtl8192u/r8192u_usb.ko | grep alias
	alias:          usb:v043Ep7A01d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v5A57p0290d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v2001p3301d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v1740p9201d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v0DF6p0031d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v050Dp805Ed*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v07AAp0043d*dc*dsc*dp*ic*isc*ip*in*
	alias:          usb:v0BDAp8709d*dc*dsc*dp*ic*isc*ip*in*

see the "v" and "p" portions of the alias string.

thanks,

greg k-h