Suspend to RAM - freeze & sync

Suspend to RAM - freeze & sync

[Radek Pilar]

[-- Attachment #1: Type: text/plain, Size: 826 bytes --]

Hello,
I'm trying to implement feature that removes cryptsetup keys from RAM on
suspend to RAM: mounts ramfs, unpacks initramfs to ramfs, moves /proc
/dev and /sys to ramfs, chroots, calls luksSuspend, suspends system
using /sys/power/state, after resume calls luksResume and cleans up.
However, there is a small issue I wasn't able to solve: after calling
luksSuspend, all attempts to access suspended device blocks - so most
likely some processes won't be able to freeze. The same issue will be
with sync just before suspend - if there are some data to be written,
sync() blocks. If I comment out freeze and sync from the suspend code,
it suspends (and wakes up) just fine - however, that patch will never be
accepted.
Is there any *correct* way to do this? (Skip freeze/sync on demand)?
Thanks
Radek Pilar


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]

Re: Suspend to RAM - freeze & sync

[Pavel Machek]

Hi!
> I'm trying to implement feature that removes cryptsetup keys from RAM on
> suspend to RAM: mounts ramfs, unpacks initramfs to ramfs, moves /proc
> /dev and /sys to ramfs, chroots, calls luksSuspend, suspends system
> using /sys/power/state, after resume calls luksResume and cleans up.
> However, there is a small issue I wasn't able to solve: after calling
> luksSuspend, all attempts to access suspended device blocks - so most
> likely some processes won't be able to freeze. The same issue will be
> with sync just before suspend - if there are some data to be written,
> sync() blocks. If I comment out freeze and sync from the suspend code,
> it suspends (and wakes up) just fine - however, that patch will never be
> accepted.
> Is there any *correct* way to do this? (Skip freeze/sync on demand)?

Maybe uswsusp interface is powerful enough to do this?
									Pavel


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html