Messages in this thread | | | Date | Tue, 27 Jan 2015 13:33:39 +0800 | From | Jiang Liu <> | Subject | Re: [PATCH] genirq: MSI: Fix freeing of unallocated MSI |
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On 2015/1/27 3:10, Marc Zyngier wrote: > While debugging an unrelated issue with the GICv3 ITS driver, the > following trace triggered: > > WARNING: CPU: 1 PID: 1 at kernel/irq/irqdomain.c:1121 irq_domain_free_irqs+0x160/0x17c() > NULL pointer, cannot free irq > Modules linked in: > CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 3.19.0-rc6+ #3690 > Hardware name: FVP Base (DT) > Call trace: > [<ffffffc000089398>] dump_backtrace+0x0/0x13c > [<ffffffc0000894e4>] show_stack+0x10/0x1c > [<ffffffc00066d134>] dump_stack+0x74/0x94 > [<ffffffc0000a92f8>] warn_slowpath_common+0x9c/0xd4 > [<ffffffc0000a938c>] warn_slowpath_fmt+0x5c/0x80 > [<ffffffc0000ee04c>] irq_domain_free_irqs+0x15c/0x17c > [<ffffffc0000ef918>] msi_domain_free_irqs+0x58/0x74 > [<ffffffc000386f58>] free_msi_irqs+0xb4/0x1c0 > > // The msi_prepare callback fails here > > [<ffffffc0003872c0>] pci_enable_msix+0x25c/0x3d4 > [<ffffffc00038746c>] pci_enable_msix_range+0x34/0x80 > [<ffffffc0003924ac>] vp_try_to_find_vqs+0xec/0x528 > [<ffffffc000392954>] vp_find_vqs+0x6c/0xa8 > [<ffffffc0003ee2a8>] init_vq+0x120/0x248 > [<ffffffc0003eefb0>] virtblk_probe+0xb0/0x6bc > [<ffffffc00038fc34>] virtio_dev_probe+0x17c/0x214 > [<ffffffc0003d4a04>] driver_probe_device+0x7c/0x23c > [<ffffffc0003d4cb0>] __driver_attach+0x98/0xa0 > [<ffffffc0003d2c60>] bus_for_each_dev+0x60/0xb4 > [<ffffffc0003d455c>] driver_attach+0x1c/0x28 > [<ffffffc0003d41b0>] bus_add_driver+0x150/0x208 > [<ffffffc0003d54c0>] driver_register+0x64/0x130 > [<ffffffc00038f9e8>] register_virtio_driver+0x24/0x68 > [<ffffffc00091320c>] init+0x70/0xac > [<ffffffc0000828f0>] do_one_initcall+0x94/0x1d0 > [<ffffffc0008e9b00>] kernel_init_freeable+0x144/0x1e4 > [<ffffffc00066a434>] kernel_init+0xc/0xd8 > ---[ end trace f9ee562a77cc7bae ]--- > > The ITS msi_prepare callback having failed, we end-up trying to > free MSIs that have never been allocated. Oddly enough, the kernel > is pretty upset about it. > > It turns out that this behaviour was expected before the MSI domain > was introduced (and dealt with in arch_teardown_msi_irqs). > > The obvious fix is to detect this early enough and bail out. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > kernel/irq/msi.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c > index 3e18163..474de5c 100644 > --- a/kernel/irq/msi.c > +++ b/kernel/irq/msi.c > @@ -310,8 +310,15 @@ void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev) > struct msi_desc *desc; > > for_each_msi_entry(desc, dev) { > - irq_domain_free_irqs(desc->irq, desc->nvec_used); > - desc->irq = 0; > + /* > + * We might have failed to allocate an MSI early > + * enough that there is no IRQ associated to this > + * entry. If that's the case, don't do anything. > + */ > + if (desc->irq) { > + irq_domain_free_irqs(desc->irq, desc->nvec_used); > + desc->irq = 0; > + } > } > } > > Review-by: Jiang Liu <jiang.liu@linux.intel.com>
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