Messages in this thread | | | Subject | Re: How to create kernel semaphore that will timeout? | From | Andi Kleen <> | Date | 12 Oct 1999 15:06:30 +0200 |
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Matthew.Wilcox@genedata.com (Matthew Wilcox) writes:
> On Mon, Oct 11, 1999 at 04:00:50PM -0500, Bret Indrelee wrote: > > What is the best way to create a kernel semaphore that will time out after > > so many clock ticks? > > > > The normal kernel semaphore code doesn't provide a timeout value, if you > > wait it is assumed to be OK to wait forever. > > > > One of the things I would like to do with such a semaphore is to implement a > > timeout on DMA transfers, such that if the transfer doesn't complete in so > > much time it will give up. I would also like to implement some simple device > > locking using it. > > Why not just use a timer which unlocks the semaphore after a given period?
You can unlock a semaphore which you're holding, but there is no clean to cancel a pending semaphore down request, which would be required for down_trylock_timeout().
Workaround: use a wait queue and schedule_timeout.
-Andi
-- This is like TV. I don't like TV.
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