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SubjectRe: [PATCH v2 1/6] hwrng: core: Freeze khwrng thread during suspend
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 <>
> Cc: Herbert Xu <>
> Cc: Duncan Laurie <>
> Signed-off-by: Stephen Boyd <>
> ---
> drivers/char/hw_random/core.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)

Do you want this to go through the crypto tree? If so you need
to cc the linux-crypto mailing list.

Email: Herbert Xu <>
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