Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 29 Dec 2003 11:43:29 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: Add support for checking before-the-fact whether an IRQ is |
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On Mon, 29 Dec 2003, Arjan van de Ven wrote: > On Mon, 2003-12-29 at 19:18, Linux Kernel Mailing List wrote: > > ChangeSet 1.1552, 2003/12/29 10:18:11-08:00, torvalds@home.osdl.org > > > > Add support for checking before-the-fact whether an IRQ is > > already registered or not. The x86 PCI layer wants this for > > its availability testing. > > > > Doing a request_irq()/free_irq() pair to check this condition > > like we used to do can lock the machine if the irq happens to > > be screaming. > > > question; which lock prevents someone else claiming the irq and making > it unsharable/unclaimable between can_request_irq() and the eventual > request_irq() ????
Nothing. It never did. This is basically a heuristic: "find the irq that looks the least used".
I just fixed the heuristic so that it shouldn't cause problems if the system comes up with the BIOS having done something silly like leaving an irq pending..
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