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SubjectRe: Suspend/Resume Broken on AM43/AM33 Platforms
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On 19/08/19 11:57 AM, Stephen Boyd wrote:
> Quoting Keerthy (2019-08-18 21:24:58)
>> Hi Stephen,
>>
>> commit 03a3bb7ae63150230c5de645dc95e673ebf17e1a
>> Author: Stephen Boyd <swboyd@chromium.org>
>> Date: Mon Aug 5 16:32:41 2019 -0700
>>
>> hwrng: core - Freeze khwrng thread during suspend
>>
>> Commit seems to be breaking suspend/resume on TI AM43/AM33 platforms.
>>
>>
>> rtcwake: wakeup from "mem" using /dev/rtc0 at Sun Nov 18 02:12:12 2018
>> [ 54.033833] PM: suspend entry (deep)
>> [ 54.037741] Filesystems sync: 0.000 seconds
>> [ 54.062730] Freezing user space processes ... (elapsed 0.001 seconds)
>> done.
>> [ 54.071313] OOM killer disabled.
>> [ 54.074572] Freezing remaining freezable tasks ...
>> [ 74.083121] Freezing of tasks failed after 20.003 seconds (1 tasks
>> refusing to freeze, wq_busy=0):
>> [ 74.092257] hwrng R running task 0 289 2
>> 0x00000020
>> [ 74.099511] [<c08c64c4>] (__schedule) from [<c08c6a10>]
>> (schedule+0x3c/0xc0)
>> [ 74.106720] [<c08c6a10>] (schedule) from [<c05dbd8c>]
>> (add_hwgenerator_randomness+0xb0/0x100)
>> [ 74.115358] [<c05dbd8c>] (add_hwgenerator_randomness) from
>> [<bf1803c8>] (hwrng_fillfn+0xc0/0x14c [rng_core])
>
> Thanks for the report. I suspect we need to check for freezer in
> add_hwgenerator_randomness(). I find it odd that there's another caller
> of add_hwgenerator_randomness(), but maybe the ath9k driver can be
> converted to some sort of hwrng driver instead of calling into the
> kthread directly.
>
> Anyway, can you try this patch?

I applied the below patch on top of latest next branch.

Fixes the issue.

Thanks,
Keerthy

>
> ---8<---
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 5d5ea4ce1442..e2e85ca16410 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -2429,6 +2429,7 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
> size_t entropy)
> {
> struct entropy_store *poolp = &input_pool;
> + bool frozen = false;
>
> if (unlikely(crng_init == 0)) {
> crng_fast_load(buffer, count);
> @@ -2439,9 +2440,12 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
> * We'll be woken up again once below random_write_wakeup_thresh,
> * or when the calling thread is about to terminate.
> */
> - wait_event_interruptible(random_write_wait, kthread_should_stop() ||
> + wait_event_interruptible(random_write_wait,
> + kthread_freezable_should_stop(&frozen) ||
> ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
> - mix_pool_bytes(poolp, buffer, count);
> - credit_entropy_bits(poolp, entropy);
> + if (!frozen) {
> + mix_pool_bytes(poolp, buffer, count);
> + credit_entropy_bits(poolp, entropy);
> + }
> }
> EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
>

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