Messages in this thread | | | Date | Wed, 18 Jun 2003 17:20:39 -0700 | From | Greg KH <> | Subject | Re: [PATCH] udev enhancements to use kernel event queue |
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On Wed, Jun 18, 2003 at 05:12:50PM -0700, Kevin P. Fleming wrote: > Greg KH wrote: > > >>If this kmalloc fails, you'll have a hole in the numbers and > >>user space will be very confused. You need to report dropped > >>events if you do this. > > > > > >Yes, we should add the sequence number last. > > > > While this is not a bad idea, I don't think you want to make a promise > to userspace that there will never be gaps in the sequence numbers. When > this sequence number was proposed, in my mind it seemed perfect because > then userspace could _order_ multiple events for the same device to > ensure they got processed in the correct order. I don't know that any > hotplug userspace implementation is going to be large and complex enough > to warrant "holding" events until lower-numbered events have been > delivered. That just seems like a very difficult task with little > potential gain, but I could very well be mistaken :-)
Yes you are :)
You will have to handle gaps properly yes.
But you also have to "hold" events for a bit of time in order to determine that things are out of order, or we have a gap. So a bit of "complex" logic is in the works, but it's much less complex than if we didn't have that sequence number.
thanks,
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