netdev - Re: [PATCH net-next] ibmvnic: Don't handle RX interrupts when not up.

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Message-Id: <9244dd27-37b5-62cc-89f9-1528ee92d40a@linux.vnet.ibm.com>
Date:   Wed, 10 Jan 2018 10:46:47 -0600
From:   Nathan Fontenot <nfont@...ux.vnet.ibm.com>
To:     Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>, netdev@...r.kernel.org
Cc:     jallen@...ux.vnet.ibm.com
Subject: Re: [PATCH net-next] ibmvnic: Don't handle RX interrupts when not up.

On 01/09/2018 02:33 PM, Thomas Falcon wrote:
> On 01/08/2018 10:09 AM, Nathan Fontenot wrote:
>> Initiating a kdump via the command line can cause a pending interrupt
>> to be handled by the ibmvnic driver when initializing the sub-CRQ
>> irqs during driver initialization.
>>
>> NIP [d000000000ca34f0] ibmvnic_interrupt_rx+0x40/0xd0 [ibmvnic]
>> LR [c000000008132ef0] __handle_irq_event_percpu+0xa0/0x2f0
>> Call Trace:
>> [c000000047fcfde0] [c000000008132ef0] __handle_irq_event_percpu+0xa0/0x2f0
>> [c000000047fcfea0] [c00000000813317c] handle_irq_event_percpu+0x3c/0x90
>> [c000000047fcfee0] [c00000000813323c] handle_irq_event+0x6c/0xd0
>> [c000000047fcff10] [c0000000081385e0] handle_fasteoi_irq+0xf0/0x250
>> [c000000047fcff40] [c0000000081320a0] generic_handle_irq+0x50/0x80
>> [c000000047fcff60] [c000000008014984] __do_irq+0x84/0x1d0
>> [c000000047fcff90] [c000000008027564] call_do_irq+0x14/0x24
>> [c00000003c92af00] [c000000008014b70] do_IRQ+0xa0/0x120
>> [c00000003c92af50] [c000000008002594] hardware_interrupt_common+0x114/0x180
>> --- interrupt: 501 at arch_local_irq_restore+0x74/0x90
>>     LR = arch_local_irq_restore+0x74/0x90
>> [c00000003c92b240] [c000000008138a20] irq_startup+0xa0/0xe0 (unreliable)
>> [c00000003c92b260] [c0000000087fc440] _raw_spin_unlock_irqrestore+0x40/0x70
>> [c00000003c92b280] [c0000000081361f4] __setup_irq+0x584/0x7a0
>> [c00000003c92b420] [c0000000081366a0] request_threaded_irq+0x140/0x290
>> [c00000003c92b480] [d000000000ca3754] init_sub_crq_irqs+0x1d4/0x370 [ibmvnic]
>> [c00000003c92b520] [d000000000ca6b50] ibmvnic_init+0x140/0x760 [ibmvnic]
>> [c00000003c92b5c0] [d000000000ca7308] ibmvnic_probe+0x198/0x330 [ibmvnic]
>> [c00000003c92b650] [c000000008037270] vio_bus_probe+0x1c0/0x480
>> [c00000003c92b6f0] [c00000000859a140] driver_probe_device+0x1f0/0x540
>> [c00000003c92b780] [c00000000859a59c] __driver_attach+0x10c/0x110
>> [c00000003c92b7c0] [c000000008596dac] bus_for_each_dev+0x8c/0xf0
>> [c00000003c92b810] [c000000008599798] driver_attach+0x38/0x50
>> [c00000003c92b830] [c000000008598f68] bus_add_driver+0x2b8/0x380
>> [c00000003c92b8c0] [c00000000859b660] driver_register+0xa0/0x180
>> [c00000003c92b930] [c000000008035c5c] __vio_register_driver+0x7c/0xc0
>> [c00000003c92b9b0] [d000000000caaf3c] ibmvnic_module_init+0x5c/0x70 [ibmvnic]
>> [c00000003c92ba10] [c00000000800b6cc] do_one_initcall+0x12c/0x280
>> [c00000003c92bae0] [c000000008805614] do_init_module+0x98/0x24c
>> [c00000003c92bb70] [c000000008181a80] load_module+0x1470/0x16c0
>> [c00000003c92bd40] [c000000008181fb0] SyS_finit_module+0xd0/0x120
>> [c00000003c92be30] [c000000008009204] system_call+0x38/0xb4
>>
>> At this poibnt the driver is not prepared to handle traffic and
>> should not try to handle the interrupt. This patch adds a check to
>> ensure the driver is up when handling RX interrupots.
>>
>> Signed-off-by: Nathan Fontenot <nfont@...ux.vnet.ibm.com>
>> ---
> 
> Minor comments:
> 
> There is a typo in the commit message.

Oops! Will fix in next version.

> 
>>  drivers/net/ethernet/ibm/ibmvnic.c |    3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
>> index 6911b7cc06c5..46990b84cb2d 100644
>> --- a/drivers/net/ethernet/ibm/ibmvnic.c
>> +++ b/drivers/net/ethernet/ibm/ibmvnic.c
>> @@ -2453,6 +2453,9 @@ static irqreturn_t ibmvnic_interrupt_rx(int irq, void *instance)
>>  	struct ibmvnic_sub_crq_queue *scrq = instance;
>>  	struct ibmvnic_adapter *adapter = scrq->adapter;
>>
>> +	if (adapter->state != VNIC_OPEN)
>> +		return IRQ_NONE;
>> +
> 
> Could you include a comment that this is a kdump specific check, since in any other case interrupts should be disabled if the device is closed?  Maybe you could use unlikely() here too.

Yes, I can add this update to the next version.

-Nathan

> 
> Thanks,
> Tom
> 
>>  	adapter->rx_stats_buffers[scrq->scrq_num].interrupts++;
>>
>>  	if (napi_schedule_prep(&adapter->napi[scrq->scrq_num])) {
>>
>