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SubjectRe: Today Linus redesigns the networking driver interface (was Re: tulip driver in ...)
Donald Becker writes:
> On Mon, 21 Sep 1998, Gerard Roudier wrote:
> > > Wouldn't these problems with sharing interrupts be solved by removing
> > > the SA_INTERRUPT flag entirely and simply having interrupt handlers

Please be careful with attributions: I wrote the above, not Gerard.

> As Linus explained, SA_INTERRUPT has a specific use in the serial
> drivers, and was excellent for that use. The bug was using it in
> the SCSI drivers.

Yeah, I agree. If you're not going to mark a BH active, then the cost
of checking for them is trivial, so why ask the kernel to avoid BH
processing? In all but the serial driver, surely the cost of
processing an interrupt is far greater than doing the BH check?

So a heuristic to avoid BH processing isn't really worthwhile, I now
think, nor is a return flag from interrupt handlers saying "please
don't process BH's now", since the (bh_active & bh_mask) test is good
enough.
The simple rule: "if you haven't registered/marked active a BH, then
you aren't going to trigger BH processing, so don't worry about it"
seems like the right thing.

Regards,

Richard....

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