Re: [PATCH V2 net-next 08/12] net: hns3: stop schedule reset service while unloading driver

[tanhuazhong]

On 2019/4/24 21:55, Neil Horman wrote:
> On Wed, Apr 24, 2019 at 07:05:27PM +0800, Huazhong Tan wrote:
> > This patch uses HCLGE_STATE_REMOVING/HCLGEVF_STATE_REMOVING flag to
> > indicate that the driver is unloading, and we should stop new coming
> > reset service to be scheduled, otherwise, reset service will access
> > some resource which has been freed by unloading.
> >
> > Signed-off-by: Huazhong Tan <tanhuazhong@xxxxxxxxxx>
> > Signed-off-by: Peng Li <lipeng321@xxxxxxxxxx>
> > ---
> > V1->V2: fixes a flag setting error
> > ---
> >   drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c   | 4 +++-
> >   drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c | 4 +++-
> >   drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.h | 1 +
> >   3 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
> > index 4d5568e..ead8308 100644
> > --- a/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
> > +++ b/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_main.c
> > @@ -2175,7 +2175,8 @@ static void hclge_mbx_task_schedule(struct hclge_dev *hdev)
> >   
> >   static void hclge_reset_task_schedule(struct hclge_dev *hdev)
> >   {
> > -	if (!test_and_set_bit(HCLGE_STATE_RST_SERVICE_SCHED, &hdev->state))
> > +	if (!test_bit(HCLGE_STATE_REMOVING, &hdev->state) &&
> > +	    !test_and_set_bit(HCLGE_STATE_RST_SERVICE_SCHED, &hdev->state))
> >   		schedule_work(&hdev->rst_service_task);
> >   }
> >   
>
> In what use case do you need an extra bit for this?  From my read, this work
> task only gets scheduled from:
> 1) Interrupt handlers
> 2) Its own service task
>
> Based on the fact that you are calling cancel_work_sync(...rst_service_task)
> from the pci teardown routine, irqs should all be disabled on your devices
> already (meaning interrupts shouldn't schedule it), and cancel_work_sync
> guarantees that rearming cant happen from within its own service task.
>
> Neil

Beside these two cases, when the client detects an error and requests a 
reset, it will call hclge_reset_event and schedule the reset work task 
to deal with the request. This may happen after calling 
cancel_work_sync(...rst_service_task) from the pci teardown routine.

Best Regards, Huazhong

> .