[PATCH] cxl: Avoid double free_irq() for psl,slice interrupts

[Andrew Donnellan]

On 29/05/17 21:57, Vaibhav Jain wrote:
> During an eeh call to cxl_remove can result in double free_irq of
> psl,slice interrupts. This can happen if perst_reloads_same_image == 1
> and call to cxl_configure_adapter() fails during slot_reset
> callback. In such a case we see a kernel oops with following back-trace:
>
> Oops: Kernel access of bad area, sig: 11 [#1]
> Call Trace:
>   free_irq+0x88/0xd0 (unreliable)
>   cxl_unmap_irq+0x20/0x40 [cxl]
>   cxl_native_release_psl_irq+0x78/0xd8 [cxl]
>   pci_deconfigure_afu+0xac/0x110 [cxl]
>   cxl_remove+0x104/0x210 [cxl]
>   pci_device_remove+0x6c/0x110
>   device_release_driver_internal+0x204/0x2e0
>   pci_stop_bus_device+0xa0/0xd0
>   pci_stop_and_remove_bus_device+0x28/0x40
>   pci_hp_remove_devices+0xb0/0x150
>   pci_hp_remove_devices+0x68/0x150
>   eeh_handle_normal_event+0x140/0x580
>   eeh_handle_event+0x174/0x360
>   eeh_event_handler+0x1e8/0x1f0
>
> This patch fixes the issue of double free_irq by checking that
> variables that hold the virqs (err_hwirq, serr_hwirq, psl_virq) are
> not '0' before un-mapping and resetting these variables to '0' when
> they are un-mapped.
>
> Signed-off-by: Vaibhav Jain <vaibhav at linux.vnet.ibm.com>

Cc stable?

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

> ---
>  drivers/misc/cxl/native.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
> index 871a2f0..3ed2254 100644
> --- a/drivers/misc/cxl/native.c
> +++ b/drivers/misc/cxl/native.c
> @@ -1302,13 +1302,16 @@ int cxl_native_register_psl_err_irq(struct cxl *adapter)
>
>  void cxl_native_release_psl_err_irq(struct cxl *adapter)
>  {
> -	if (adapter->native->err_virq != irq_find_mapping(NULL, adapter->native->err_hwirq))
> +	if (adapter->native->err_virq == 0 ||
> +	    adapter->native->err_virq !=
> +	    irq_find_mapping(NULL, adapter->native->err_hwirq))
>  		return;
>
>  	cxl_p1_write(adapter, CXL_PSL_ErrIVTE, 0x0000000000000000);
>  	cxl_unmap_irq(adapter->native->err_virq, adapter);
>  	cxl_ops->release_one_irq(adapter, adapter->native->err_hwirq);
>  	kfree(adapter->irq_name);
> +	adapter->native->err_virq = 0;
>  }
>
>  int cxl_native_register_serr_irq(struct cxl_afu *afu)
> @@ -1346,13 +1349,15 @@ int cxl_native_register_serr_irq(struct cxl_afu *afu)
>
>  void cxl_native_release_serr_irq(struct cxl_afu *afu)
>  {
> -	if (afu->serr_virq != irq_find_mapping(NULL, afu->serr_hwirq))
> +	if (afu->serr_virq == 0 ||
> +	    afu->serr_virq != irq_find_mapping(NULL, afu->serr_hwirq))
>  		return;
>
>  	cxl_p1n_write(afu, CXL_PSL_SERR_An, 0x0000000000000000);
>  	cxl_unmap_irq(afu->serr_virq, afu);
>  	cxl_ops->release_one_irq(afu->adapter, afu->serr_hwirq);
>  	kfree(afu->err_irq_name);
> +	afu->serr_virq = 0;
>  }
>
>  int cxl_native_register_psl_irq(struct cxl_afu *afu)
> @@ -1375,12 +1380,15 @@ int cxl_native_register_psl_irq(struct cxl_afu *afu)
>
>  void cxl_native_release_psl_irq(struct cxl_afu *afu)
>  {
> -	if (afu->native->psl_virq != irq_find_mapping(NULL, afu->native->psl_hwirq))
> +	if (afu->native->psl_virq == 0 ||
> +	    afu->native->psl_virq !=
> +	    irq_find_mapping(NULL, afu->native->psl_virq))
>  		return;
>
>  	cxl_unmap_irq(afu->native->psl_virq, afu);
>  	cxl_ops->release_one_irq(afu->adapter, afu->native->psl_hwirq);
>  	kfree(afu->psl_irq_name);
> +	afu->native->psl_virq = 0;
>  }
>
>  static void recover_psl_err(struct cxl_afu *afu, u64 errstat)
>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited