Re: [Intel-wired-lan] [PATCH] igb: Unconditionally deallocate workqueues as allocation already does

[Tony Nguyen <anthony.l.nguyen@intel.com>]

On 7/18/2023 6:45 AM, Alessio Igor Bogani wrote:
> The workqueues ptp_tx_work and ptp_overflow_work are unconditionally allocated
> by igb_ptp_init() but, at the moment, are deallocated only if the flag
> IGB_PTP_ENABLED is on which isn't the case if there are errors or
> if CONFIG_PTP is disabled.
> 
> Otherwise, when we unbind the igb driver with vfio-pci we receive a stack trace:
> BUG: unable to handle page fault for address: ffffc9000440b6f8
> [...]
> Workqueue: events igb_ptp_overflow_check
> RIP: 0010:igb_rd32+0x1f/0x60
> [...]
> Call Trace:
>   igb_ptp_read_82580+0x20/0x50
>   timecounter_read+0x15/0x60
>   igb_ptp_overflow_check+0x1a/0x50
>   process_one_work+0x1cb/0x3c0
>   worker_thread+0x53/0x3f0
>   ? rescuer_thread+0x370/0x370
>   kthread+0x142/0x160
>   ? kthread_associate_blkcg+0xc0/0xc0
>   ret_from_fork+0x1f/0x30

Process-wise. If you can please specify the tree you are targeting and, 
as this is a fix, you should add a Fixes: tag.

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html#netdev-faq

This is also missing your sign-off

> ---
>   drivers/net/ethernet/intel/igb/igb_ptp.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
> index 6f471b91f562..56839bf65c13 100644
> --- a/drivers/net/ethernet/intel/igb/igb_ptp.c
> +++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
> @@ -1440,9 +1440,6 @@ void igb_ptp_sdp_init(struct igb_adapter *adapter)
>    */
>   void igb_ptp_suspend(struct igb_adapter *adapter)
>   {
> -	if (!(adapter->ptp_flags & IGB_PTP_ENABLED))
> -		return;
> -

There are cases where the workqueues are not setup (and IGB_PTP_ENABLED 
not set); this safeguards against those situations. I think the better 
fix would be to not have the workqueues if PTP is not enabled.

>   	if (adapter->ptp_flags & IGB_PTP_OVERFLOW_CHECK)
>   		cancel_delayed_work_sync(&adapter->ptp_overflow_work);
>   
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