Re: IRQF_DISABLED problem

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David Miller wrote:
From: Arjan van de Ven <[email protected]>
Date: Fri, 27 Jul 2007 13:11:56 -0700

On Thu, 2007-07-26 at 16:17 -0700, Linus Torvalds wrote:
On Thu, 26 Jul 2007, Linus Torvalds wrote:
(c) "one IRQF_DISABLED means that everything runs disabled". This is quite possibly buggy.
(Side note: I'm not claiming this (or it's mirror image (d)) is really any better/worse than the current behaviour from a theoretical standpoint, but at least the current behaviour is _tested_, which makes it better in practice. So if we want to change this, I think we want to change it to something that is _obviously_ better).
my personal preference would actually be to just never enable
interrupts. It's the fastest solution obviously, the most friendly on
stack and.. well simplest. Drivers no longer need to play some of the
games that they do today. And while there is an argument that this may
introduce a bit of latency... I'm not really convinced.

If you have a "chirpy" serial controller with only a 1 byte
fifo, even a quite reasonable interrupt handler can cause
receive characters to get lost if you disable interrupts during
the entirety of it's execution.

It really is needed.

And it's just plain rude to disable interrupts when it isn't
absolutely necessary.

Does anyone really use those serial controllers with no FIFO anymore? They've never been reliable for remotely high speeds..

--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/

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