From: Eugene Surovegin <[EMAIL PROTECTED]> Date: Tue, 6 Sep 2005 00:40:01 -0700
> According to Documentation/networking/netdevices.txt > dev->hard_start_xmit must be called with interrupts *enabled*. > > Unfortunately, current netconsole code always calls netpoll with local > interrupts disabled: > > write_msg (local_irq_save) > netpoll_send_udp > netpoll_send_skb > np->dev->hard_start_xmit. > > I'm not sure this can cause any problems, but quick grep has showed > that some drivers indeed rely on the documented behavior. > > Also, it'd be nice if netpoll author updated netdevices.txt with info > about dev->poll_controller sync rules :) (in fact, I stumbled upon > this inconsistency when I was trying to figure out locking for > dev->poll_controller implementation in my driver). Yes, several drivers rely on interrupts being enabled, I learned this the hard way in the past. Also, disabling interrupts during this potentially expensive function call can kill your interrupt latency sensitive devices (such as serial ports) and allow them to overflow. I don't immediately see how this can be fixed, because the console code does really need to disable interrupts in order to not try to recursively take it's locks. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
