[PATCH iwl-net v2 4/6] ice: check ICE_VSI_DOWN under rtnl_lock when preparing for reset

[Larysa Zaremba]

Consider the following scenario:

.ndo_bpf()		| ice_prepare_for_reset()		|
________________________|_______________________________________|
rtnl_lock()		|					|
ice_down()		|					|
			| test_bit(ICE_VSI_DOWN) - true		|
			| ice_dis_vsi() returns			|
ice_up()		|					|
			| proceeds to rebuild a running VSI	|

.ndo_bpf() is not the only rtnl-locked callback that toggles the interface
to apply new configuration. Another example is .set_channels().

To avoid the race condition above, act only after reading ICE_VSI_DOWN
under rtnl_lock.

Fixes: 0f9d5027a749 ("ice: Refactor VSI allocation, deletion and rebuild flow")
Reviewed-by: Wojciech Drewek <wojciech.drewek@xxxxxxxxx>
Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
---
 drivers/net/ethernet/intel/ice/ice_lib.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
index f9852f1a136e..b773078ad81a 100644
--- a/drivers/net/ethernet/intel/ice/ice_lib.c
+++ b/drivers/net/ethernet/intel/ice/ice_lib.c
@@ -2665,8 +2665,7 @@ int ice_ena_vsi(struct ice_vsi *vsi, bool locked)
  */
 void ice_dis_vsi(struct ice_vsi *vsi, bool locked)
 {
-	if (test_bit(ICE_VSI_DOWN, vsi->state))
-		return;
+	bool already_down = test_bit(ICE_VSI_DOWN, vsi->state);
 
 	set_bit(ICE_VSI_NEEDS_RESTART, vsi->state);
 
@@ -2674,15 +2673,16 @@ void ice_dis_vsi(struct ice_vsi *vsi, bool locked)
 		if (netif_running(vsi->netdev)) {
 			if (!locked)
 				rtnl_lock();
-
-			ice_vsi_close(vsi);
+			already_down = test_bit(ICE_VSI_DOWN, vsi->state);
+			if (!already_down)
+				ice_vsi_close(vsi);
 
 			if (!locked)
 				rtnl_unlock();
-		} else {
+		} else if (!already_down) {
 			ice_vsi_close(vsi);
 		}
-	} else if (vsi->type == ICE_VSI_CTRL) {
+	} else if (vsi->type == ICE_VSI_CTRL && !already_down) {
 		ice_vsi_close(vsi);
 	}
 }
-- 
2.43.0