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SubjectRe: [PATCH v2] staging: rtl8192u: Fix sleep in atomic context bug in dm_fsync_timer_callback
Hello,

On Thu, 23 Jun 2022 11:46:41 +0200 Greg KH wrote:

> 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@zju.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.

Best regards,
Duoming Zhou
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