Quoting Jarkko Sakkinen (2019-08-02 13:22:09)
> On Tue, Jul 16, 2019 at 03:45:13PM -0700, Stephen Boyd wrote:
> > The hwrng_fill() function can run while devices are suspending and
> > resuming. If the hwrng is behind a bus such as i2c or SPI and that bus
> > is suspended, the hwrng may hang the bus while attempting to add some
> > randomness. It's been observed on ChromeOS devices with suspend-to-idle
> > (s2idle) and an i2c based hwrng that this kthread may run and ask the
> > hwrng device for randomness before the i2c bus has been resumed.
> >
> > Let's make this kthread freezable so that we don't try to touch the
> > hwrng during suspend/resume. This ensures that we can't cause the hwrng
> > backing driver to get into a bad state because the device is guaranteed
> > to be resumed before the hwrng kthread is thawed.
> >
> > Cc: Andrey Pronin <apronin@xxxxxxxxxxxx>
> > Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> > Cc: Duncan Laurie <dlaurie@xxxxxxxxxxxx>
> > Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
>
> This does not need a fixes tag?
>
I'll add Fixes: be4000bc4644 ("hwrng: create filler thread")
