Re: [PATCH 0/8] Suspend block api (version 6)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, May 13, 2010 at 02:34:55PM -0700, Tony Lindgren wrote:
> * Matthew Garrett <mjg@xxxxxxxxxx> [100513 14:16]:
> > What race-free mechanism do you use to ensure that? It's very easy to 
> > handwave these problems away. It's very difficult to actually write an 
> > implementation that works.
> 
> Can you describe where do you see the race now?

1) Trusted app decides to suspend
2) Network packet that would otherwise wake the system is received
3) Trusted app sends SIGSTOP to untrusted userspace
4) Network packet sits waiting for stopped userspace to process it

Unless the trusted userspace gets woken up on every event that would 
potentially cause a wakeup, you're racy. And the alternative involves an 
extra userspace wakeup for every network packet - which is expensive.

-- 
Matthew Garrett | mjg59@xxxxxxxxxxxxx
_______________________________________________
linux-pm mailing list
linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/linux-pm

[Index of Archives]     [Linux ACPI]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [CPU Freq]     [Kernel Newbies]     [Fedora Kernel]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]

  Powered by Linux