Re: [PATCH] net/mlx4: Fix EEH recovery failure

Or Gerlitz
2014-11-25T22:00:32Z

On Mon, Nov 24, 2014 at 11:55 PM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
> On Mon, Nov 24, 2014 at 11:17:55PM +0200, Or Gerlitz wrote:
>>On Sat, Nov 22, 2014 at 12:56 PM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
>>> The patch fixes couple of EEH recovery failures on PPC PowerNV
>>> platform:
>>
>>> * Don't clear struct mlx4_priv instance in mlx4_pci_err_detected().
>>> Otherwise, __mlx4_init_one() runs into kernel crash because
>>> of dereferencing to NULL pointer.
>>
>>I don't see this change in the patch, I see no-clearing of mlx4_priv
>>in __mlx4_unload_one - please clarify, also is this patch
>>based/targeted on the net or net-next tree?
>>
>
> Yes, It would be: Don't clear struct mlx4_priv instance in mlx4_unload_one(),
> which is called by mlx4_pci_err_detected().

But the struct mlx4_priv instance is cleared in mlx4_unload_one() for
a reason, I suspect that you might made the EEH callback to work, but
broke something else... e.g did you made sure that kexec works after
your changes as it did before?

> It's based on 3.18.rc5, where I had couple of EEH fixes on top of it.
> When testing EEH with it, I hit the issue.

>>> With the patch applied, EEH recovery for mlx4 adapter succeeds on PPC
>>> PowerNV platform.
>>>
>>> # lspci
>>> 0003:0f:00.0 Network controller: Mellanox Technologies \
>>> MT27500 Family [ConnectX-3]
>>>
>>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>>> ---
>>> drivers/net/ethernet/mellanox/mlx4/main.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
>>> index 90de6e1..e118ac9 100644
>>> --- a/drivers/net/ethernet/mellanox/mlx4/main.c
>>> +++ b/drivers/net/ethernet/mellanox/mlx4/main.c
>>> @@ -2809,7 +2809,6 @@ static void mlx4_unload_one(struct pci_dev *pdev)
>>> kfree(dev->caps.qp1_proxy);
>>> kfree(dev->dev_vfs);
>>>
>>> - memset(priv, 0, sizeof(*priv));
>>> priv->pci_dev_data = pci_dev_data;
>>> priv->removed = 1;
>>> }
>>> @@ -2900,6 +2899,8 @@ static pci_ers_result_t mlx4_pci_err_detected(struct pci_dev *pdev,
>>> pci_channel_state_t state)
>>> {
>>> mlx4_unload_one(pdev);
>>> + pci_release_regions(pdev);
>>> + pci_disable_device(pdev);
>>>
>>> return state == pci_channel_io_perm_failure ?
>>> PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_NEED_RESET;
>>> --