[PATCH v4] iommu/arm-smmu: avoid calling request_irq in atomic context

[Will Deacon]

On Wed, Jul 30, 2014 at 06:58:13PM +0100, Mitchel Humpherys wrote:
> request_irq shouldn't be called from atomic context since it might
> sleep, but we're calling it with a spinlock held, resulting in:
> 
>     [    9.172202] BUG: sleeping function called from invalid context at kernel/mm/slub.c:926
>     [    9.182989] in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper/0
>     [    9.189762] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W    3.10.40-gbc1b510b-38437-g55831d3bd9-dirty #97
>     [    9.199757] [<c020c448>] (unwind_backtrace+0x0/0x11c) from [<c02097d0>] (show_stack+0x10/0x14)
>     [    9.208346] [<c02097d0>] (show_stack+0x10/0x14) from [<c0301d74>] (kmem_cache_alloc_trace+0x3c/0x210)
>     [    9.217543] [<c0301d74>] (kmem_cache_alloc_trace+0x3c/0x210) from [<c0276a48>] (request_threaded_irq+0x88/0x11c)
>     [    9.227702] [<c0276a48>] (request_threaded_irq+0x88/0x11c) from [<c0931ca4>] (arm_smmu_attach_dev+0x188/0x858)
>     [    9.237686] [<c0931ca4>] (arm_smmu_attach_dev+0x188/0x858) from [<c0212cd8>] (arm_iommu_attach_device+0x18/0xd0)
>     [    9.247837] [<c0212cd8>] (arm_iommu_attach_device+0x18/0xd0) from [<c093314c>] (arm_smmu_test_probe+0x68/0xd4)
>     [    9.257823] [<c093314c>] (arm_smmu_test_probe+0x68/0xd4) from [<c05aadd0>] (driver_probe_device+0x12c/0x330)
>     [    9.267629] [<c05aadd0>] (driver_probe_device+0x12c/0x330) from [<c05ab080>] (__driver_attach+0x68/0x8c)
>     [    9.277090] [<c05ab080>] (__driver_attach+0x68/0x8c) from [<c05a92d4>] (bus_for_each_dev+0x70/0x84)
>     [    9.286118] [<c05a92d4>] (bus_for_each_dev+0x70/0x84) from [<c05aa3b0>] (bus_add_driver+0x100/0x244)
>     [    9.295233] [<c05aa3b0>] (bus_add_driver+0x100/0x244) from [<c05ab5d0>] (driver_register+0x9c/0x124)
>     [    9.304347] [<c05ab5d0>] (driver_register+0x9c/0x124) from [<c0933088>] (arm_smmu_test_init+0x14/0x38)
>     [    9.313635] [<c0933088>] (arm_smmu_test_init+0x14/0x38) from [<c0200618>] (do_one_initcall+0xb8/0x160)
>     [    9.322926] [<c0200618>] (do_one_initcall+0xb8/0x160) from [<c1200b7c>] (kernel_init_freeable+0x108/0x1cc)
>     [    9.332564] [<c1200b7c>] (kernel_init_freeable+0x108/0x1cc) from [<c0b924b0>] (kernel_init+0xc/0xe4)
>     [    9.341675] [<c0b924b0>] (kernel_init+0xc/0xe4) from [<c0205e38>] (ret_from_fork+0x14/0x3c)
> 
> Fix this by moving the request_irq out of the critical section. This
> should be okay since smmu_domain->smmu is still being protected by the
> critical section. Also, we still don't program the Stream Match Register
> until after registering our interrupt handler so we shouldn't be missing
> any interrupts.
> 
> Signed-off-by: Mitchel Humpherys <mitchelh at codeaurora.org>
> ---
> Changelog:
> 
>   - v4: some cleanup suggested by Will
>   - v3: rework irq request code to avoid requesting the irq every
>         time a master is added to the domain
>   - v2: return error code from request_irq on failure
> ---
>  drivers/iommu/arm-smmu.c | 49 +++++++++++++++++++++++++-----------------------
>  1 file changed, 26 insertions(+), 23 deletions(-)

Great, thanks Mitch. I'll queue this for 3.18.

Will