Locking netatm

Kris Kennaway kris at obsecurity.org
Sun May 28 22:18:13 PDT 2006


On Mon, May 29, 2006 at 01:52:48PM +0900, gnn at FreeBSD.org wrote:

> > So my question is, were network interrupts disabled when mucking
> > with the atm_timeq list because a generated interrupt can modify
> > structures within the list?  This use is probably very
> > netatm-specific.  I'm still studying the timeout code to understand
> > what it's doing.
> > 
> 
> The spl() calls haven't disabled real interrupts, as far as I know,
> for quite a while.  They acted as general code locks to prevent
> simultaneous access to data structures while an update was in
> progress.  In terms of the timeq, the locks were acting as a mutex now
> would to protect the list during an update.

Actually the spl calls have all been NOPs since the early 5.0 days,
and they were just left in an mnemonic placeholders showing which
code/data sections need to be protected.

Kris
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