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genirq: MSI: Fix freeing of unallocated MSI 

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>
Reviewed-by: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1422299419-6051-1-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Marc Zyngier 2015-01-26 19:10:19 +00:00 committed by Thomas Gleixner
parent 462b69b1e4
commit fe0c52fc00
1 changed files with 9 additions and 2 deletions
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11
kernel/irq/msi.c
View File

@ -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;
}
}
}