From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Subject: Re: 3.16rc3 multiplatform, Armada 370 and IOMMU: unbootable kernel Date: Tue, 8 Jul 2014 09:41:49 +0200 Message-ID: <20140708094149.0ad6ab13@free-electrons.com> References: <20140703135146.GA6898@luxor.wired.org> <53B5C61D.2060308@free-electrons.com> <53B5CA26.7050405@free-electrons.com> <1936558.QaAG1bYMuD@avalon> <20140705150308.GA28791@arch.cereza> <20140705205951.GB3678@kroah.com> <20140707105818.GA1101@arch.cereza> <20140707183002.GA5947@kroah.com> <20140707233758.GA1456@arch.cereza> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140707233758.GA1456@arch.cereza> Sender: linux-kernel-owner@vger.kernel.org To: Ezequiel Garcia Cc: Greg Kroah-Hartman , Paolo Pisati , Andrew Lunn , Jason Cooper , Joerg Roedel , Hiroshi.DOYU@nokia.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Laurent Pinchart , Gregory CLEMENT , Sebastian Hesselbarth , Florian Vaussard , linux-arm-kernel@lists.infradead.org List-Id: iommu@lists.linux-foundation.org Dear Ezequiel Garcia, On Mon, 7 Jul 2014 20:37:58 -0300, Ezequiel Garcia wrote: > It seems bus_register_notifier() is been called for platform and pci devices > with the *same* notifier block. Haven't looked close enough, but you mentioned > that could cause trouble? > > This patch fixes the issue here: > > diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c > index 477202f..2bdc323 100644 > --- a/arch/arm/mach-mvebu/coherency.c > +++ b/arch/arm/mach-mvebu/coherency.c > @@ -292,6 +292,10 @@ static struct notifier_block mvebu_hwcc_nb = { > .notifier_call = mvebu_hwcc_notifier, > }; > > +static struct notifier_block mvebu_hwcc_pci_nb = { > + .notifier_call = mvebu_hwcc_notifier, > +}; > + > static void __init armada_370_coherency_init(struct device_node *np) > { > struct resource res; > @@ -427,7 +431,7 @@ static int __init coherency_pci_init(void) > { > if (coherency_available()) > bus_register_notifier(&pci_bus_type, > - &mvebu_hwcc_nb); > + &mvebu_hwcc_pci_nb); > return 0; > } > > Paolo, can you apply it and confirm it fixes the problem? > > Greg, can you confirm using the same notifier block pointer > for two different bus types makes the bus notifier go nuts? Looking at how notifier_chain_register() is implemented (which gets called by bus_register_notifier() -> blocking_notifier_chain_register()), I indeed don't see how a single 'struct notifier_block' can be registered on multiple notifier chains, so I believe your patch is correct. Thanks for the investigation! Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com