Messages in this thread | | | Subject | Re: [linux-pm] [PATCH] Threads shouldn't inherit PF_NOFREEZE | From | Nigel Cunningham <> | Date | Thu, 20 Oct 2005 07:01:17 +1000 |
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Hi Alan.
On Wed, 2005-10-19 at 05:29, Alan Stern wrote: > The PF_NOFREEZE process flag should not be inherited when a thread is > forked. This patch (as585) removes the flag from the child. > > This problem is starting to show up more and more as drivers turn to the > kthread API instead of using kernel_thread(). As a result, their kernel > threads are now children of the kthread worker instead of modprobe, and > they inherit the PF_NOFREEZE flag. This can cause problems during system > suspend; the kernel threads are not getting frozen as they ought to be. > > Alan Stern
I have this in kthread instead, so that multithreaded userspace processes only need to have NOFREEZE set once (before forking). Yes, I have one that fits this scenario - I'm working on a userspace storage maanger, which will setup and tear down a network connection at appropriate times during a suspend-to-disk cycle. The initial version is based on nbd and uses two threads because the one that sets up storage blocks in a syscall as Pavel & others have written it.
Anyway, I agree that the general need you're trying to address is real.
Regards,
Nigel
> > > Signed-off-by: Alan Stern <stern@rowland.harvard.edu> > > --- > > What I said above may not be quite true. For all I know, there may be > threads which rely on inheriting PF_NOFREEZE from their parent. But it > should not be inherited by default. > > Index: usb-2.6/kernel/fork.c > =================================================================== > --- usb-2.6.orig/kernel/fork.c > +++ usb-2.6/kernel/fork.c > @@ -848,7 +848,7 @@ static inline void copy_flags(unsigned l > { > unsigned long new_flags = p->flags; > > - new_flags &= ~PF_SUPERPRIV; > + new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE); > new_flags |= PF_FORKNOEXEC; > if (!(clone_flags & CLONE_PTRACE)) > p->ptrace = 0; > > > ______________________________________________________________________ > _______________________________________________ > linux-pm mailing list > linux-pm@lists.osdl.org > https://lists.osdl.org/mailman/listinfo/linux-pm --
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