On Wed Apr 26, 2023 at 4:32 AM EEST, Jason A. Donenfeld wrote: > Nice work! Happy that you got it figured out. That trace seems > consistent with what I was seeing in my traces, so I think you've > spotted the right bug. > > Jason Unfortunately there might be two bugs. Unless I interpreted logs incorrectly also hwrng can race with resume (sorry, I forgot to save it). Looking at drivers/char/hw_random/core.c there seems to be no binding to the PM so I guess that this it supports what I'm observing [*]. So there's two ways to fix the issue: 1. Unregister hwrng for the course of suspend 2. Add something like TPM_CHIP_SUSPENDED, which is set by suspend and cleared by the resume. I try the 2nd option first because I see it less complicated. Probably would make sense to turn chip flags as atomic while at it. [*] https://elixir.bootlin.com/linux/latest/source/drivers/char/hw_random/core.c BR, Jarkko
