On Tue, Sep 06, 2005 at 06:03:38PM -0700, Matt Mackall wrote: > On Tue, Sep 06, 2005 at 04:01:24PM -0700, David S. Miller wrote: > > So you cannot call into these drivers with HW interrupts disabled or > > even worse from HW interrupt context. These drivers use locking > > strategies which are perfectly legal and work until you add netpoll. > > And again, I agree. > > What I disagree with is the claim that it's netpoll that's "broken". > Again, I claim that netpoll is not doing something fundamentally > unreasonable. Driving hardware by polling with interrupts disabled is > nothing magic, it's just something the network stack to date has not > been designed to cope with.
Well, it's not driving hw in polling mode with hw IRQs disabled (in fact, NAPI does exactly this), it's _calling_ driver entry points from illegal context. IMHO this is not the same. > So we can either: > > a) have a netpoll that's crippled to softirq-only > b) live with some amount of localized brain damage here > c) attempt to make the stack more netpoll-accomodating or a') make this a per-driver feature (e.g. NETIF_F_NETPOLL_CHALENGED) In this case, even if driver cannot handle being called from IRQ context, netconsole still can be used, although in a little more limited fashion, but being safe and not causing lock ups, which, as far as I understand you, it was designed to help debugging in the first place :). -- Eugene - 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
