[PATCH v2 1/1][SRU][J] ice: avoid bonding causing auxiliary plug/unplug under RTNL lock

[Tim Gardner]

On 3/31/23 6:22 AM, Heitor Alves de Siqueira wrote:
> From: Dave Ertman <david.m.ertman at intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2004262
> 
> RDMA is not supported in ice on a PF that has been added to a bonded
> interface. To enforce this, when an interface enters a bond, we unplug
> the auxiliary device that supports RDMA functionality.  This unplug
> currently happens in the context of handling the netdev bonding event.
> This event is sent to the ice driver under RTNL context.  This is causing
> a deadlock where the RDMA driver is waiting for the RTNL lock to complete
> the removal.
> 
> Defer the unplugging/re-plugging of the auxiliary device to the service
> task so that it is not performed under the RTNL lock context.
> 
> Cc: stable at vger.kernel.org # 6.1.x
> Reported-by: Jaroslav Pulchart <jaroslav.pulchart at gooddata.com>
> Link: https://lore.kernel.org/netdev/CAK8fFZ6A_Gphw_3-QMGKEFQk=sfCw1Qmq0TVZK3rtAi7vb621A@mail.gmail.com/
> Fixes: 5cb1ebdbc434 ("ice: Fix race condition during interface enslave")
> Fixes: 4eace75e0853 ("RDMA/irdma: Report the correct link speed")
> Signed-off-by: Dave Ertman <david.m.ertman at intel.com>
> Tested-by: Arpana Arland <arpanax.arland at intel.com> (A Contingent worker at Intel)
> Signed-off-by: Tony Nguyen <anthony.l.nguyen at intel.com>
> Reviewed-by: Leon Romanovsky <leonro at nvidia.com>
> Link: https://lore.kernel.org/r/20230310194833.3074601-1-anthony.l.nguyen@intel.com
> Signed-off-by: Jakub Kicinski <kuba at kernel.org>
> (backported from commit 248401cb2c4612d83eb0c352ee8103b78b8eb365)
> Signed-off-by: Heitor Alves de Siqueira <halves at canonical.com>
> ---
>   drivers/net/ethernet/intel/ice/ice.h      | 14 +++++---------
>   drivers/net/ethernet/intel/ice/ice_main.c | 19 ++++++++-----------
>   2 files changed, 13 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
> index 89bca2ed895a..2d67876c53a6 100644
> --- a/drivers/net/ethernet/intel/ice/ice.h
> +++ b/drivers/net/ethernet/intel/ice/ice.h
> @@ -399,6 +399,7 @@ enum ice_pf_flags {
>   	ICE_FLAG_MDD_AUTO_RESET_VF,
>   	ICE_FLAG_LINK_LENIENT_MODE_ENA,
>   	ICE_FLAG_PLUG_AUX_DEV,
> +	ICE_FLAG_UNPLUG_AUX_DEV,
>   	ICE_FLAG_MTU_CHANGED,
>   	ICE_PF_FLAGS_NBITS		/* must be last */
>   };
> @@ -706,16 +707,11 @@ static inline void ice_set_rdma_cap(struct ice_pf *pf)
>    */
>   static inline void ice_clear_rdma_cap(struct ice_pf *pf)
>   {
> -	/* We can directly unplug aux device here only if the flag bit
> -	 * ICE_FLAG_PLUG_AUX_DEV is not set because ice_unplug_aux_dev()
> -	 * could race with ice_plug_aux_dev() called from
> -	 * ice_service_task(). In this case we only clear that bit now and
> -	 * aux device will be unplugged later once ice_plug_aux_device()
> -	 * called from ice_service_task() finishes (see ice_service_task()).
> +	/* defer unplug to service task to avoid RTNL lock and
> +	 * clear PLUG bit so that pending plugs don't interfere
>   	 */
> -	if (!test_and_clear_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags))
> -		ice_unplug_aux_dev(pf);
> -
> +	clear_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags);
> +	set_bit(ICE_FLAG_UNPLUG_AUX_DEV, pf->flags);
>   	clear_bit(ICE_FLAG_RDMA_ENA, pf->flags);
>   	clear_bit(ICE_FLAG_AUX_ENA, pf->flags);
>   }
> diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
> index ffbba5f6b7a5..d3462fc650d1 100644
> --- a/drivers/net/ethernet/intel/ice/ice_main.c
> +++ b/drivers/net/ethernet/intel/ice/ice_main.c
> @@ -2156,18 +2156,15 @@ static void ice_service_task(struct work_struct *work)
>   		}
>   	}
>   
> -	if (test_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags)) {
> -		/* Plug aux device per request */
> -		ice_plug_aux_dev(pf);
> +	/* unplug aux dev per request, if an unplug request came in
> +	 * while processing a plug request, this will handle it
> +	 */
> +	if (test_and_clear_bit(ICE_FLAG_UNPLUG_AUX_DEV, pf->flags))
> +		ice_unplug_aux_dev(pf);
>   
> -		/* Mark plugging as done but check whether unplug was
> -		 * requested during ice_plug_aux_dev() call
> -		 * (e.g. from ice_clear_rdma_cap()) and if so then
> -		 * plug aux device.
> -		 */
> -		if (!test_and_clear_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags))
> -			ice_unplug_aux_dev(pf);
> -	}
> +	/* Plug aux device per request */
> +	if (test_and_clear_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags))
> +		ice_plug_aux_dev(pf);
>   
>   	if (test_and_clear_bit(ICE_FLAG_MTU_CHANGED, pf->flags)) {
>   		struct iidc_event *event;

This is a clean cherry pick for me. Do you have some cruft in your tree 
preventing clean application ? Also, when you declare that a patch is a 
backport you should describe what changes you had to make in order to 
get the patch to apply. For example,

(backported from commit 248401cb2c4612d83eb0c352ee8103b78b8eb365)
[Heitor - simple context adjustments]

-- 
-----------
Tim Gardner
Canonical, Inc