Messages in this thread | | | Date | Thu, 26 Jun 2003 20:44:46 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH] Provide refrigerator support for irda |
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Hi!
> > > Admittedly I didn't care about swsusp so far. Given the big fat warning on > > > top of Documentation/swsusp.txt I would not even try and i personally > > > don't see what I would miss without swsusp. > > > > That's okay... Just support your DMA-ing devices are supported. > > No matter whether it would be ISA-DMA or PCI busmastering I guess?
Any DMA is a problem.
> Not sure whether we can claim most irda drivers ready for swsusp then. > vlsi_ir should be fine and for irda-usb I assume it would be up to the > hcd - but don't know about the others...
Well, at least SIR should work as it works over normal serial, IIRC.
> > If it is possible to sleep at place "a", and no locks needed for > > suspend are held at "a", inserting > > > > if (current->flags & PF_FREEZE) > > refrigerator(PF_IOTHREAD); > > > > is the right thing to do. > > Ok, so the proposed patch is doing the right thing and should be applied. > > Pavel, two more questions: > > * For a kernel compiled with CONFIG_SWSUSP=n, may I assume PF_FREEZE would > never be set or at least refrigerator would be noop?
PF_FREEZE is 0 so if() never succeeds.
> * Isn't there a race on SMP (and probably UP with CONFIG_PREEMPT) when > PF_FREEZE gets modified by another cpu right after the test?
Only task itself ever clears its PF_FREEZE. That means there should be no problem. Pavel
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