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Date: Mon, 9 Nov 2009 16:32:31 +0300 From: Anton Vorontsov <avorontsov@...mvista.com> To: David Miller <davem@...emloft.net> Cc: afleming@...escale.com, jason.wessel@...driver.com, netdev@...r.kernel.org, linuxppc-dev@...abs.org Subject: Re: [PATCH RFC] gianfar: Make polling safe with IRQs disabled On Sun, Nov 08, 2009 at 01:05:33AM -0800, David Miller wrote: ... > > When using KGDBoE, gianfar driver spits 'Interrupt problem' messages, > > which appears to be a legitimate warning, i.e. we may end up calling > > netif_receive_skb() or vlan_hwaccel_receive_skb() with IRQs disabled. > > > > This patch reworks the RX path so that if netpoll is enabled (the > > only case when the driver don't know from what context the polling > > may be called), we check whether IRQs are disabled, and if so we > > fall back to safe variants of skb receiving functions. > > This is bogus, I'll tell you why. > > When you go into netif_receive_skb() we have a special check, > "if (netpoll_receive_skb(..." that takes care of all of the > details concerning doing a ->poll() from IRQ disabled context > via netpoll. > > So this code you're adding should not be necessary. > > Or, explain to me why no other driver needs special logic in their > ->poll() handler like this and does not run into any kinds of netpoll > problems :-) Hm, I was confused by the following note: /** * netif_receive_skb - process receive buffer from network * @skb: buffer to process ... * This function may only be called from softirq context and interrupts * should be enabled. Looking into the code though, I can indeed see that there are netpoll checks, and __netpoll_rx() is actually called with irqs disabled. So, in the end it appears that we should just remove the 'Interrupt problem' message. Thanks! -- Anton Vorontsov email: cbouatmailru@...il.com irc://irc.freenode.net/bd2 -- 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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