From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yingjoe Chen Subject: Re: [PATCH v7 1/4] irqchip: gic: Support hierarchy irq domain. Date: Thu, 20 Nov 2014 17:41:51 +0800 Message-ID: <1416476511.12869.24.camel@mtksdaap41> References: <1416406451-4578-1-git-send-email-yingjoe.chen@mediatek.com> <1416406451-4578-2-git-send-email-yingjoe.chen@mediatek.com> <87h9xvaz2p.fsf@approximate.cambridge.arm.com> <1416455840.12869.17.camel@mtksdaap41> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1416455840.12869.17.camel@mtksdaap41> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marc Zyngier Cc: Thomas Gleixner , Jiang Liu , Mark Rutland , Boris BREZILLON , Russell King , Jason Cooper , Pawel Moll , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "hc.yen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" , "srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" , "yh.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , Yijing Wang , Rob Herring , "nathan.chung-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" , "yingjoe.chen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , Matthias Brugger , "eddie.huang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" List-Id: devicetree@vger.kernel.org Hi Marc, On Thu, 2014-11-20 at 11:57 +0800, Yingjoe Chen wrote: > On Wed, 2014-11-19 at 17:18 +0000, Marc Zyngier wrote: > > > + > > > + return 0; > > > +} > > > + > > > +static const struct irq_domain_ops gic_irq_domain_hierarchy_ops = { > > > + .xlate = gic_irq_domain_xlate, > > > + .alloc = gic_irq_domain_alloc, > > > + .free = irq_domain_free_irqs_top, > > > > I'm convinced that irq_domain_free_irqs_top is the wrong function to > > call here, because you're calling it from the bottom, not the top-level > > (it has no parent). > > Base on the name, I though this is helper function for top level > irq_domain? > > > I cannot verify this with your code as I don't a working platform with > > GICv2m, but if I enable something similar on GICv3, it dies a very > > painful way: > > > > Unable to handle kernel NULL pointer dereference at virtual address 00000018 > > pgd = ffffffc03d059000 > > [00000018] *pgd=0000000081356003, *pud=0000000081356003, *pmd=0000000000000000 > > Internal error: Oops: 96000006 [#1] SMP > > Modules linked in: > > CPU: 4 PID: 1052 Comm: sh Not tainted 3.18.0-rc4+ #3311 > > task: ffffffc03e320000 ti: ffffffc001390000 task.ti: ffffffc001390000 > > PC is at irq_domain_free_irqs_recursive+0x1c/0x80 > > LR is at irq_domain_free_irqs_common+0x88/0x9c > > pc : [] lr : [] pstate: 60000145 > > [...] > > [] irq_domain_free_irqs_recursive+0x1c/0x80 > > [] irq_domain_free_irqs_common+0x84/0x9c > > [] irq_domain_free_irqs_top+0x64/0x7c <-- gic_domain.free() > > [] irq_domain_free_irqs_recursive+0x24/0x80 > > [] irq_domain_free_irqs_parent+0x14/0x20 > > [] its_irq_domain_free+0xc8/0x250 > > [] irq_domain_free_irqs_recursive+0x24/0x80 > > [] irq_domain_free_irqs_common+0x84/0x9c > > [] irq_domain_free_irqs_top+0x64/0x7c > > [] msi_domain_free+0x70/0x88 > > [] irq_domain_free_irqs_recursive+0x24/0x80 > > [] irq_domain_free_irqs+0x108/0x17c > > [] msi_domain_free_irqs+0x28/0x4c > > [] free_msi_irqs+0xb4/0x1c0 > > [] pci_disable_msix+0x3c/0x4c > > [...] > > > > and I cannot see how this could work on the standard GIC either. > > I'm sorry, I just realize my testcase was too simple, irqs are populated > by device tree and never got freed. I'll add that and test it again. On a second thoughts, unlike the MSI cases, gic_irq_domain_hierarchy_ops is only used when we use DT, so we probably will never use the free function. Is it OK to remove the free support here? Joe.C -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html