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From: Marek Lindner <lindner_marek@yahoo.de>
To: The list for a Better Approach To Mobile Ad-hoc Networking
	<b.a.t.m.a.n@lists.open-mesh.net>
Subject: Re: [B.A.T.M.A.N.] [PATCH] batman-adv: Use forw_bcast_list_lock always in disabled interrupt context
Date: Thu, 17 Dec 2009 21:11:39 +0800	[thread overview]
Message-ID: <200912172111.40169.lindner_marek@yahoo.de> (raw)
In-Reply-To: <1261051915-13960-1-git-send-email-sven.eckelmann@gmx.de>

On Thursday 17 December 2009 20:11:55 Sven Eckelmann wrote:
> forw_bcast_list_lock is spin_locked in both process and softirq context.
> SoftIRQ calls the spinlock with disabled IRQ and normal process context
> with enabled IRQs.
> 
> When process context is inside an spin_locked area protected by
> forw_bcast_list_lock and gets interrupted by an IRQ, it could happen
> that something tries to lock forw_bcast_list_lock again in SoftIRQ
> context. It cannot proceed further since the lock is already taken
> somewhere else, but no reschedule will happen inside the SoftIRQ
> context. This leads to an complete kernel hang without any chance of
> resurrection.
> 
> All functions called in process context must disable IRQs when they try
> to get get that lock to to prevent any reschedule due to IRQs.

Thanks - nice catch (applied in rev 1504)! 

Regards,
Marek

      parent reply	other threads:[~2009-12-17 13:11 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-17 12:11 [B.A.T.M.A.N.] [PATCH] batman-adv: Use forw_bcast_list_lock always in disabled interrupt context Sven Eckelmann
2009-12-17 12:25 ` Andrew Lunn
2009-12-17 14:34   ` Sven Eckelmann
2009-12-17 14:47     ` Sven Eckelmann
2009-12-17 13:11 ` Marek Lindner [this message]

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