[S11,06/16] ice: fix ice_remove_rule_internal vsi_list handling

Message ID 20190208205043.11975-7-anirudh.venkataramanan@intel.com
State Under Review
Delegated to: Jeff Kirsher
Headers show
Series
  • Bug fixes for ice
Related show

Commit Message

Anirudh Venkataramanan Feb. 8, 2019, 8:50 p.m.
From: Jacob Keller <jacob.e.keller@intel.com>

When adding multiple VLANs to the same VSI, the ice_add_vlan code will
share the VSI list, so as not to create multiple unnecessary VSI lists.

Consider the following flow

  ice_add_vlan(hw, <VSI 0 VID 7, VSI 0 VID 8, VSI 0 VID 9>)

Where we add three VLAN filters for VIDs 7, 8, and 9, all for VSI 0.

The ice_add_vlan will create a single vsi_list and share it among all
the filters.

Later, if we try to remove a VLAN,

  ice_remove_vlan(hw, <VSI 0 VID 7>)

Then the removal code will update the vsi_list and remove VSI 0 from it.
But, since the vsi_list is shared, this breaks the list for the other
users who reference it. We actually even free the VSI list memory, and
may result in segmentation faults.

This is due to the way that VLAN rule share VSI lists with reference
counts, and is caused because we call ice_rem_update_vsi_list even when
the ref_cnt is greater than one.

To fix this, handle the case where ref_cnt is greater than one
separately. In this case, we need to remove the associated rule without
modifying the vsi_list, since it is currently being referenced by
another rule. Instead, we just need to decrement the VSI list ref_cnt.

The case for handling sharing of VSI lists with multiple VSIs is not
currently supported by this code. No such rules will be created today,
and this code will require changes if/when such code is added.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
---
[Anirudh Venkataramanan <anirudh.venkataramanan@intel.com> cleaned up commit message]
---
 drivers/net/ethernet/intel/ice/ice_switch.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Comments

Bowers, AndrewX Feb. 14, 2019, 11:50 p.m. | #1
> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On
> Behalf Of Anirudh Venkataramanan
> Sent: Friday, February 8, 2019 12:51 PM
> To: intel-wired-lan@lists.osuosl.org
> Subject: [Intel-wired-lan] [PATCH S11 06/16] ice: fix
> ice_remove_rule_internal vsi_list handling
> 
> From: Jacob Keller <jacob.e.keller@intel.com>
> 
> When adding multiple VLANs to the same VSI, the ice_add_vlan code will
> share the VSI list, so as not to create multiple unnecessary VSI lists.
> 
> Consider the following flow
> 
>   ice_add_vlan(hw, <VSI 0 VID 7, VSI 0 VID 8, VSI 0 VID 9>)
> 
> Where we add three VLAN filters for VIDs 7, 8, and 9, all for VSI 0.
> 
> The ice_add_vlan will create a single vsi_list and share it among all the filters.
> 
> Later, if we try to remove a VLAN,
> 
>   ice_remove_vlan(hw, <VSI 0 VID 7>)
> 
> Then the removal code will update the vsi_list and remove VSI 0 from it.
> But, since the vsi_list is shared, this breaks the list for the other users who
> reference it. We actually even free the VSI list memory, and may result in
> segmentation faults.
> 
> This is due to the way that VLAN rule share VSI lists with reference counts,
> and is caused because we call ice_rem_update_vsi_list even when the
> ref_cnt is greater than one.
> 
> To fix this, handle the case where ref_cnt is greater than one separately. In
> this case, we need to remove the associated rule without modifying the
> vsi_list, since it is currently being referenced by another rule. Instead, we
> just need to decrement the VSI list ref_cnt.
> 
> The case for handling sharing of VSI lists with multiple VSIs is not currently
> supported by this code. No such rules will be created today, and this code will
> require changes if/when such code is added.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> Reviewed-by: Bruce Allan <bruce.w.allan@intel.com>
> Signed-off-by: Anirudh Venkataramanan
> <anirudh.venkataramanan@intel.com>
> ---
> [Anirudh Venkataramanan <anirudh.venkataramanan@intel.com> cleaned
> up commit message]
> ---
>  drivers/net/ethernet/intel/ice/ice_switch.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers@intel.com>

Patch

diff --git a/drivers/net/ethernet/intel/ice/ice_switch.c b/drivers/net/ethernet/intel/ice/ice_switch.c
index 528b90cdd9da..bee08d1a44e0 100644
--- a/drivers/net/ethernet/intel/ice/ice_switch.c
+++ b/drivers/net/ethernet/intel/ice/ice_switch.c
@@ -1538,9 +1538,20 @@  ice_remove_rule_internal(struct ice_hw *hw, u8 recp_id,
 	} else if (!list_elem->vsi_list_info) {
 		status = ICE_ERR_DOES_NOT_EXIST;
 		goto exit;
+	} else if (list_elem->vsi_list_info->ref_cnt > 1) {
+		/* a ref_cnt > 1 indicates that the vsi_list is being
+		 * shared by multiple rules. Decrement the ref_cnt and
+		 * remove this rule, but do not modify the list, as it
+		 * is in-use by other rules.
+		 */
+		list_elem->vsi_list_info->ref_cnt--;
+		remove_rule = true;
 	} else {
-		if (list_elem->vsi_list_info->ref_cnt > 1)
-			list_elem->vsi_list_info->ref_cnt--;
+		/* a ref_cnt of 1 indicates the vsi_list is only used
+		 * by one rule. However, the original removal request is only
+		 * for a single VSI. Update the vsi_list first, and only
+		 * remove the rule if there are no further VSIs in this list.
+		 */
 		vsi_handle = f_entry->fltr_info.vsi_handle;
 		status = ice_rem_update_vsi_list(hw, vsi_handle, list_elem);
 		if (status)