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Date: Thu, 13 Dec 2007 14:02:25 -0500 From: Andrew Gallatin <gallatin@...i.com> To: Stephen Hemminger <shemminger@...ux-foundation.org> CC: David Miller <davem@...emloft.net>, joonwpark81@...il.com, auke-jan.h.kok@...el.com, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, jgarzik@...ox.com, jesse.brandeburg@...el.com Subject: Re: [RFC] net: napi fix Stephen Hemminger wrote: > On Thu, 13 Dec 2007 06:19:38 -0800 (PST) > David Miller <davem@...emloft.net> wrote: > >> From: Andrew Gallatin <gallatin@...i.com> >> Date: Thu, 13 Dec 2007 09:13:54 -0500 >> >>> If the netif_running() check is indeed required to make a device break >>> out of napi polling and respond to an ifconfig down, then I think the >>> netif_running() check should be moved up into net_rx_action() to avoid >>> potential for driver complexity and bugs like the ones you found. >> That, or something like it, definitely sounds reasonable and much >> better than putting the check into every driver :-) >> -- >> To unsubscribe from this list: send the line "unsubscribe netdev" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > It is not possible to do netif_running() check in generic code as currently > written because of the case of devices where a single NAPI object is > being used to handle two devices. The association between napi and netdevice > is M to N. There are cases like niu that have multiple NAPI's and one > netdevice; and devices like sky2 that can have one NAPI and 2 netdevice's. Ah, now I see. I forgot that not every device has a 1:1::napi:netdev relationship. Could we make an optional *dev_state field in the napi structure. It would be initialized to __LINK_STATE_START. Devices which have a 1:1 NAPI:netdevice relationship would set it to &netdev->state. The generic code would then do a test_bit(__LINK_STATE_START, napi->dev_state), and 1:1 drivers could remove this check. M:N drivers would pay for a useless (to them) test_bit, and would have to provide their own netif_running check to get termination under heavy load. Just an idea, perhaps there is a better way which is less hacky. Or perhaps we should just leave things as is. Drew -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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