ice: Avoid RTNL lock when re-creating auxiliary device

If a call to re-create the auxiliary device happens in a context that has
already taken the RTNL lock, then the call flow that recreates auxiliary
device can hang if there is another attempt to claim the RTNL lock by the
auxiliary driver.

To avoid this, any call to re-create auxiliary devices that comes from
an source that is holding the RTNL lock (e.g. netdev notifier when
interface exits a bond) should execute in a separate thread.  To
accomplish this, add a flag to the PF that will be evaluated in the
service task and dealt with there.

Fixes: f9f5301e ("ice: Register auxiliary device to provide RDMA")
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Reviewed-by: Jonathan Toppins <jtoppins@redhat.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice.h

@@ -483,6 +483,7 @@ enum ice_pf_flags {
 	ICE_FLAG_VF_TRUE_PROMISC_ENA,
 	ICE_FLAG_MDD_AUTO_RESET_VF,
 	ICE_FLAG_LINK_LENIENT_MODE_ENA,
+	ICE_FLAG_PLUG_AUX_DEV,
 	ICE_PF_FLAGS_NBITS		/* must be last */
 };
 
@@ -887,7 +888,7 @@ static inline void ice_set_rdma_cap(struct ice_pf *pf)
 	if (pf->hw.func_caps.common_cap.rdma && pf->num_rdma_msix) {
 		set_bit(ICE_FLAG_RDMA_ENA, pf->flags);
 		set_bit(ICE_FLAG_AUX_ENA, pf->flags);
-		ice_plug_aux_dev(pf);
+		set_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags);
 	}
 }
 

drivers/net/ethernet/intel/ice/ice_main.c

@@ -2253,6 +2253,9 @@ static void ice_service_task(struct work_struct *work)
 		return;
 	}
 
+	if (test_and_clear_bit(ICE_FLAG_PLUG_AUX_DEV, pf->flags))
+		ice_plug_aux_dev(pf);
+
 	ice_clean_adminq_subtask(pf);
 	ice_check_media_subtask(pf);
 	ice_check_for_hang_subtask(pf);