On Wednesday 30 September 2009 13:56:12 Oliver Hartkopp wrote:

John W. Linville wrote:

quoted

On Sat, Sep 12, 2009 at 06:41:12PM +0200, Oliver Hartkopp wrote:

quoted

i cooked a patch that introduces netif_rx_ti() and fixes up the problems in
mac80211 and the CAN subsystem.

Oliver,

Are you going to send this patch to Dave?  If you want me to carry
it instead, please resend it with a proper changelog including a
Signed-off-by line.  For that matter, Dave will most certainly want
that as well...

Hello John,

as i wrote here

http://marc.info/?l=linux-netdev&m=125277885910179&w=2

there are currently only three occurrences of checks that use netif_rx() and
netif_rx_ni() depending on in_interrupt().

And regarding the suggested fix from Michael, that checked every(!) netif_rx()
whether it is in interrupt or not, i was unsure if a netif_tx_ti() would make
sense for only three cases?!?

If you think it makes sense, i can post a patch for that ... but:

Indeed it costs some additional investigation to prove whether netif_rx() or
netif_rx_ni() should be used in each case. But IMHO this has to be done before
providing a pump-gun function that solves the problem without thinking if we
are in irq-context or not. I want to avoid that people are using netif_rx_ti()
as some kind of default ...

I don't know how expensive in_interrupt() is, but it IMO should be avoided
when the context for a code section can be determined in another way.

What if we just get the fix merged and discuss later whether it's worth to optimize a picosecond or not??
My patch fixes the _bug_. You can merge a more "efficient" fix later that saves one or two CPU cycles.

-- 
Greetings, Michael.