[PATCH net 0/4] mlxsw: Fix ACL actions error condition handling

[PATCH net 0/4] mlxsw: Fix ACL actions error condition handling

[Ido Schimmel]

Nir says:

Two issues were lately noticed within mlxsw ACL actions error condition
handling. The first patch deals with conflicting actions such as:

 # tc filter add dev swp49 parent ffff: \
   protocol ip pref 10 flower skip_sw dst_ip 192.168.101.1 \
   action goto chain 100 \
   action mirred egress redirect dev swp4

The second action will never execute, however SW model allows this
configuration, while the mlxsw driver cannot allow for it as it
implements actions in sets of up to three actions per set with a single
termination marking. Conflicting actions create a contradiction over
this single marking and thus cannot be configured. The fix replaces a
misplaced warning with an error code to be returned.

Patches 2-4 fix a condition of duplicate destruction of resources. Some
actions require allocation of specific resource prior to setting the
action itself. On error condition this resource was destroyed twice,
leading to a crash when using mirror action, and to a redundant
destruction in other cases, since for error condition rule destruction
also takes care of resource destruction. In order to fix this state a
symmetry in behavior is added and resource destruction also takes care
of removing the resource from rule's resource list.

Nir Dotan (4):
  mlxsw: core_acl_flex_actions: Return error for conflicting actions
  mlxsw: core_acl_flex_actions: Remove redundant resource destruction
  mlxsw: core_acl_flex_actions: Remove redundant counter destruction
  mlxsw: core_acl_flex_actions: Remove redundant mirror resource
    destruction

 .../mellanox/mlxsw/core_acl_flex_actions.c    | 51 +++++++++++--------
 1 file changed, 29 insertions(+), 22 deletions(-)

-- 
2.17.1

[PATCH net 1/4] mlxsw: core_acl_flex_actions: Return error for conflicting actions

[Ido Schimmel]

From: Nir Dotan <nird@mellanox.com>

Spectrum switch ACL action set is built in groups of three actions
which may point to additional actions. A group holds a single record
which can be set as goto record for pointing at a following group
or can be set to mark the termination of the lookup. This is perfectly
adequate for handling a series of actions to be executed on a packet.
While the SW model allows configuration of conflicting actions
where it is clear that some actions will never execute, the mlxsw
driver must block such configurations as it creates a conflict
over the single terminate/goto record value.

For a conflicting actions configuration such as:

 # tc filter add dev swp49 parent ffff: \
   protocol ip pref 10 \
   flower skip_sw dst_ip 192.168.101.1 \
   action goto chain 100 \
   action mirred egress mirror dev swp4

Where it is clear that the last action will never execute, the
mlxsw driver was issuing a warning instead of returning an error.
Therefore replace that warning with an error for this specific
case.

Fixes: 4cda7d8d7098 ("mlxsw: core: Introduce flexible actions support")
Signed-off-by: Nir Dotan <nird@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 .../mellanox/mlxsw/core_acl_flex_actions.c    | 42 +++++++++----------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
index 3c0d882ba183..ce280680258e 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
@@ -626,8 +626,8 @@ static char *mlxsw_afa_block_append_action(struct mlxsw_afa_block *block,
 	char *oneact;
 	char *actions;
 
-	if (WARN_ON(block->finished))
-		return NULL;
+	if (block->finished)
+		return ERR_PTR(-EINVAL);
 	if (block->cur_act_index + action_size >
 	    block->afa->max_acts_per_set) {
 		struct mlxsw_afa_set *set;
@@ -637,7 +637,7 @@ static char *mlxsw_afa_block_append_action(struct mlxsw_afa_block *block,
 		 */
 		set = mlxsw_afa_set_create(false);
 		if (!set)
-			return NULL;
+			return ERR_PTR(-ENOBUFS);
 		set->prev = block->cur_set;
 		block->cur_act_index = 0;
 		block->cur_set->next = set;
@@ -724,8 +724,8 @@ int mlxsw_afa_block_append_vlan_modify(struct mlxsw_afa_block *block,
 						  MLXSW_AFA_VLAN_CODE,
 						  MLXSW_AFA_VLAN_SIZE);
 
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_vlan_pack(act, MLXSW_AFA_VLAN_VLAN_TAG_CMD_NOP,
 			    MLXSW_AFA_VLAN_CMD_SET_OUTER, vid,
 			    MLXSW_AFA_VLAN_CMD_SET_OUTER, pcp,
@@ -806,8 +806,8 @@ int mlxsw_afa_block_append_drop(struct mlxsw_afa_block *block)
 						  MLXSW_AFA_TRAPDISC_CODE,
 						  MLXSW_AFA_TRAPDISC_SIZE);
 
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_trapdisc_pack(act, MLXSW_AFA_TRAPDISC_TRAP_ACTION_NOP,
 				MLXSW_AFA_TRAPDISC_FORWARD_ACTION_DISCARD, 0);
 	return 0;
@@ -820,8 +820,8 @@ int mlxsw_afa_block_append_trap(struct mlxsw_afa_block *block, u16 trap_id)
 						  MLXSW_AFA_TRAPDISC_CODE,
 						  MLXSW_AFA_TRAPDISC_SIZE);
 
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_trapdisc_pack(act, MLXSW_AFA_TRAPDISC_TRAP_ACTION_TRAP,
 				MLXSW_AFA_TRAPDISC_FORWARD_ACTION_DISCARD,
 				trap_id);
@@ -836,8 +836,8 @@ int mlxsw_afa_block_append_trap_and_forward(struct mlxsw_afa_block *block,
 						  MLXSW_AFA_TRAPDISC_CODE,
 						  MLXSW_AFA_TRAPDISC_SIZE);
 
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_trapdisc_pack(act, MLXSW_AFA_TRAPDISC_TRAP_ACTION_TRAP,
 				MLXSW_AFA_TRAPDISC_FORWARD_ACTION_FORWARD,
 				trap_id);
@@ -908,8 +908,8 @@ mlxsw_afa_block_append_allocated_mirror(struct mlxsw_afa_block *block,
 	char *act = mlxsw_afa_block_append_action(block,
 						  MLXSW_AFA_TRAPDISC_CODE,
 						  MLXSW_AFA_TRAPDISC_SIZE);
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_trapdisc_pack(act, MLXSW_AFA_TRAPDISC_TRAP_ACTION_NOP,
 				MLXSW_AFA_TRAPDISC_FORWARD_ACTION_FORWARD, 0);
 	mlxsw_afa_trapdisc_mirror_pack(act, true, mirror_agent);
@@ -996,8 +996,8 @@ int mlxsw_afa_block_append_fwd(struct mlxsw_afa_block *block,
 
 	act = mlxsw_afa_block_append_action(block, MLXSW_AFA_FORWARD_CODE,
 					    MLXSW_AFA_FORWARD_SIZE);
-	if (!act) {
-		err = -ENOBUFS;
+	if (IS_ERR(act)) {
+		err = PTR_ERR(act);
 		goto err_append_action;
 	}
 	mlxsw_afa_forward_pack(act, MLXSW_AFA_FORWARD_TYPE_PBS,
@@ -1052,8 +1052,8 @@ int mlxsw_afa_block_append_allocated_counter(struct mlxsw_afa_block *block,
 {
 	char *act = mlxsw_afa_block_append_action(block, MLXSW_AFA_POLCNT_CODE,
 						  MLXSW_AFA_POLCNT_SIZE);
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_polcnt_pack(act, MLXSW_AFA_POLCNT_COUNTER_SET_TYPE_PACKETS_BYTES,
 			      counter_index);
 	return 0;
@@ -1123,8 +1123,8 @@ int mlxsw_afa_block_append_fid_set(struct mlxsw_afa_block *block, u16 fid)
 	char *act = mlxsw_afa_block_append_action(block,
 						  MLXSW_AFA_VIRFWD_CODE,
 						  MLXSW_AFA_VIRFWD_SIZE);
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_virfwd_pack(act, MLXSW_AFA_VIRFWD_FID_CMD_SET, fid);
 	return 0;
 }
@@ -1193,8 +1193,8 @@ int mlxsw_afa_block_append_mcrouter(struct mlxsw_afa_block *block,
 	char *act = mlxsw_afa_block_append_action(block,
 						  MLXSW_AFA_MCROUTER_CODE,
 						  MLXSW_AFA_MCROUTER_SIZE);
-	if (!act)
-		return -ENOBUFS;
+	if (IS_ERR(act))
+		return PTR_ERR(act);
 	mlxsw_afa_mcrouter_pack(act, MLXSW_AFA_MCROUTER_RPF_ACTION_TRAP,
 				expected_irif, min_mtu, rmid_valid, kvdl_index);
 	return 0;
-- 
2.17.1

Re: [PATCH net 1/4] mlxsw: core_acl_flex_actions: Return error for conflicting actions

[Ido Schimmel]

+Stephen

On Fri, Aug 03, 2018 at 03:57:41PM +0300, Ido Schimmel wrote:
> From: Nir Dotan <nird@mellanox.com>
> 
> Spectrum switch ACL action set is built in groups of three actions
> which may point to additional actions. A group holds a single record
> which can be set as goto record for pointing at a following group
> or can be set to mark the termination of the lookup. This is perfectly
> adequate for handling a series of actions to be executed on a packet.
> While the SW model allows configuration of conflicting actions
> where it is clear that some actions will never execute, the mlxsw
> driver must block such configurations as it creates a conflict
> over the single terminate/goto record value.
...
> Where it is clear that the last action will never execute, the
> mlxsw driver was issuing a warning instead of returning an error.
> Therefore replace that warning with an error for this specific
> case.
> 
> Fixes: 4cda7d8d7098 ("mlxsw: core: Introduce flexible actions support")
> Signed-off-by: Nir Dotan <nird@mellanox.com>
> Reviewed-by: Jiri Pirko <jiri@mellanox.com>
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> ---
>  .../mellanox/mlxsw/core_acl_flex_actions.c    | 42 +++++++++----------

Dave / Stephen, please note that this is going to conflict with recent
extack changes in net-next when you merge net into net-next.

Resolution is available here:
https://github.com/jpirko/linux_mlxsw/blob/combined_queue/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c

Thanks and sorry about the conflict

[PATCH net 2/4] mlxsw: core_acl_flex_actions: Remove redundant resource destruction

[Ido Schimmel]

From: Nir Dotan <nird@mellanox.com>

Some ACL actions require the allocation of a separate resource
prior to applying the action itself. When facing an error condition
during the setup phase of the action, resource should be destroyed.
For such actions the destruction was done twice which is dangerous
and lead to a potential crash.
The destruction took place first upon error on action setup phase
and then as the rule was destroyed.

The following sequence generated a crash:

 # tc qdisc add dev swp49 ingress
 # tc filter add dev swp49 parent ffff: \
   protocol ip chain 100 pref 10 \
   flower skip_sw dst_ip 192.168.101.1 action drop
 # tc filter add dev swp49 parent ffff: \
   protocol ip pref 10 \
   flower skip_sw dst_ip 192.168.101.1 action goto chain 100 \
   action mirred egress mirror dev swp4

Therefore add mlxsw_afa_resource_del() as a complement of
mlxsw_afa_resource_add() to add symmetry to resource_list membership
handling. Call this from mlxsw_afa_fwd_entry_ref_destroy() to make the
_fwd_entry_ref_create() and _fwd_entry_ref_destroy() pair of calls a
NOP.

Fixes: 140ce421217e ("mlxsw: core: Convert fwd_entry_ref list to be generic per-block resource list")
Signed-off-by: Nir Dotan <nird@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 .../net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c    | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
index ce280680258e..d664cc0289c2 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
@@ -327,12 +327,16 @@ static void mlxsw_afa_resource_add(struct mlxsw_afa_block *block,
 	list_add(&resource->list, &block->resource_list);
 }
 
+static void mlxsw_afa_resource_del(struct mlxsw_afa_resource *resource)
+{
+	list_del(&resource->list);
+}
+
 static void mlxsw_afa_resources_destroy(struct mlxsw_afa_block *block)
 {
 	struct mlxsw_afa_resource *resource, *tmp;
 
 	list_for_each_entry_safe(resource, tmp, &block->resource_list, list) {
-		list_del(&resource->list);
 		resource->destructor(block, resource);
 	}
 }
@@ -530,6 +534,7 @@ static void
 mlxsw_afa_fwd_entry_ref_destroy(struct mlxsw_afa_block *block,
 				struct mlxsw_afa_fwd_entry_ref *fwd_entry_ref)
 {
+	mlxsw_afa_resource_del(&fwd_entry_ref->resource);
 	mlxsw_afa_fwd_entry_put(block->afa, fwd_entry_ref->fwd_entry);
 	kfree(fwd_entry_ref);
 }
-- 
2.17.1

[PATCH net 3/4] mlxsw: core_acl_flex_actions: Remove redundant counter destruction

[Ido Schimmel]

From: Nir Dotan <nird@mellanox.com>

Each tc flower rule uses a hidden count action. As counter resource may
not be available due to limited HW resources, update _counter_create()
and _counter_destroy() pair to follow previously introduced symmetric
error condition handling, add a call to mlxsw_afa_resource_del() as part
of the counter resource destruction.

Fixes: c18c1e186ba8 ("mlxsw: core: Make counter index allocated inside the action append")
Signed-off-by: Nir Dotan <nird@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
index d664cc0289c2..a54f23f00a5f 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
@@ -584,6 +584,7 @@ static void
 mlxsw_afa_counter_destroy(struct mlxsw_afa_block *block,
 			  struct mlxsw_afa_counter *counter)
 {
+	mlxsw_afa_resource_del(&counter->resource);
 	block->afa->ops->counter_index_put(block->afa->ops_priv,
 					   counter->counter_index);
 	kfree(counter);
-- 
2.17.1

[PATCH net 4/4] mlxsw: core_acl_flex_actions: Remove redundant mirror resource destruction

[Ido Schimmel]

From: Nir Dotan <nird@mellanox.com>

In previous patch mlxsw_afa_resource_del() was added to avoid a duplicate
resource detruction scenario.
For mirror actions, such duplicate destruction leads to a crash as in:

 # tc qdisc add dev swp49 ingress
 # tc filter add dev swp49 parent ffff: \
   protocol ip chain 100 pref 10 \
   flower skip_sw dst_ip 192.168.101.1 action drop
 # tc filter add dev swp49 parent ffff: \
   protocol ip pref 10 \
   flower skip_sw dst_ip 192.168.101.1 action goto chain 100 \
   action mirred egress mirror dev swp4

Therefore add a call to mlxsw_afa_resource_del() in
mlxsw_afa_mirror_destroy() in order to clear that resource
from rule's resources.

Fixes: d0d13c1858a1 ("mlxsw: spectrum_acl: Add support for mirror action")
Signed-off-by: Nir Dotan <nird@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
index a54f23f00a5f..f6f6a568d66a 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_actions.c
@@ -862,6 +862,7 @@ static void
 mlxsw_afa_mirror_destroy(struct mlxsw_afa_block *block,
 			 struct mlxsw_afa_mirror *mirror)
 {
+	mlxsw_afa_resource_del(&mirror->resource);
 	block->afa->ops->mirror_del(block->afa->ops_priv,
 				    mirror->local_in_port,
 				    mirror->span_id,
-- 
2.17.1

Re: [PATCH net 0/4] mlxsw: Fix ACL actions error condition handling

[David Miller]

From: Ido Schimmel <idosch@mellanox.com>
Date: Fri,  3 Aug 2018 15:57:40 +0300

> Nir says:
> 
> Two issues were lately noticed within mlxsw ACL actions error condition
> handling. The first patch deals with conflicting actions such as:
> 
>  # tc filter add dev swp49 parent ffff: \
>    protocol ip pref 10 flower skip_sw dst_ip 192.168.101.1 \
>    action goto chain 100 \
>    action mirred egress redirect dev swp4
> 
> The second action will never execute, however SW model allows this
> configuration, while the mlxsw driver cannot allow for it as it
> implements actions in sets of up to three actions per set with a single
> termination marking. Conflicting actions create a contradiction over
> this single marking and thus cannot be configured. The fix replaces a
> misplaced warning with an error code to be returned.
> 
> Patches 2-4 fix a condition of duplicate destruction of resources. Some
> actions require allocation of specific resource prior to setting the
> action itself. On error condition this resource was destroyed twice,
> leading to a crash when using mirror action, and to a redundant
> destruction in other cases, since for error condition rule destruction
> also takes care of resource destruction. In order to fix this state a
> symmetry in behavior is added and resource destruction also takes care
> of removing the resource from rule's resource list.

Series applied, and queued up for -stable.

And thanks especially for the merge conflict heads up.