Do not deprecate binary semaphore or do allow mutex in software interrupt contexts

[Matti Linnanvuori]

Peter Zijlstra <peterz@xxxxxxxxxxxxx>:
> Yes it is.

Why do you think it is broken?

> If you have to wait a long time in an atomic context you've done
> something wrong.

I saw an implementation where there were two atomic contexts, one to initiate reading and another to complete the reading. 
That way, there was no busy wait for a long time in an atomic context.

> If you're only reading it from an atomic context you
> might consider storing a copy that can be quickly updated and protect
> that using a spinlock.

You suggested that a user-space task read from the device. 
But that includes more context switching and therefore consumes more resources than reading just from an atomic context.

> Not being too familiar with the timer stuff, it smells wrong what you
> say.

Why?




      Wissenswertes für Bastler und Hobby Handwerker. BE A BETTER HEIMWERKER! www.yahoo.de/clever
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/