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Date: Wed, 29 Oct 2014 20:53:37 +0100 (CET) From: Thomas Gleixner <tglx@...utronix.de> To: Jeff Kirsher <jeffrey.t.kirsher@...el.com> cc: Peter Zijlstra <peterz@...radead.org>, Sabrina Dubroca <sd@...asysnail.net>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: e1000_netpoll(): disable_irq() triggers might_sleep() on linux-next On Wed, 29 Oct 2014, Jeff Kirsher wrote: > On Wed, 2014-10-29 at 20:36 +0100, Peter Zijlstra wrote: > > On Wed, Oct 29, 2014 at 07:33:00PM +0100, Thomas Gleixner wrote: > > > Yuck. No. You are just papering over the problem. > > > > > > What happens if you add 'threadirqs' to the kernel command line? Or if > > > the interrupt line is shared with a real threaded interrupt user? > > > > > > The proper solution is to have a poll_lock for e1000 which serializes > > > the hardware interrupt against netpoll instead of using > > > disable/enable_irq(). > > > > > > In fact that's less expensive than the disable/enable_irq() dance and > > > the chance of contention is pretty low. If done right it will be a > > > NOOP for the CONFIG_NET_POLL_CONTROLLER=n case. > > > > > > > OK a little something like so then I suppose.. But I suspect most all > > the network drivers will need this and maybe more, disable_irq() is a > > popular little thing and we 'just' changed semantics on them. > > Thomas- if you are fine with Peter's patch, I can get this under > testing. I'm fine with it except for the comment part of disable_irq(), but that does not matter :) One nitpick: Instead of having the lock unconditionally, I'd make it depend on CONFIG_NET_POLL_CONTROLLER. #ifdef CONFIG_NET_POLL_CONTROLLER static inline void netpoll_lock(struct e1000_adapter *adapter) { spin_lock(&adapter->irq_lock); } static inline void netpoll_unlock(struct e1000_adapter *adapter) { spin_unlock(&adapter->irq_lock); } #else static inline void netpoll_lock(struct e1000_adapter *adapter) { } static inline void netpoll_unlock(struct e1000_adapter *adapter) { } #endif and use that instead of the unconditional spin[un]lock() invocations. But that's up to you. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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