[PATCH net] net: flow_offload: skip hw stats check for FLOW_ACTION_HW_STATS_DONT_CARE

[Pablo Neira Ayuso <pablo@netfilter.org>]

This patch adds FLOW_ACTION_HW_STATS_DONT_CARE which tells the driver
that the frontend does not need counters, this hw stats type request
never fails. The FLOW_ACTION_HW_STATS_DISABLED type explicitly requests
the driver to disable the stats, however, if the driver cannot disable
counters, it bails out.

Remove BUILD_BUG_ON since TCA_ACT_HW_STATS_* don't map 1:1 with
FLOW_ACTION_HW_STATS_* anymore. Add tc_act_hw_stats() to perform the
mapping between TCA_ACT_HW_STATS_* and FLOW_ACTION_HW_STATS_*

Fixes: 319a1d19471e ("flow_offload: check for basic action hw stats type")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
This is a follow up after "net: flow_offload: skip hw stats check for
FLOW_ACTION_HW_STATS_DISABLED". This patch restores the netfilter hardware
offloads.

 include/net/flow_offload.h |  9 ++++++++-
 net/sched/cls_api.c        | 23 +++++++++++++++++------
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
index 3619c6acf60f..0c75163699f0 100644
--- a/include/net/flow_offload.h
+++ b/include/net/flow_offload.h
@@ -164,12 +164,15 @@ enum flow_action_mangle_base {
 };
 
 enum flow_action_hw_stats_bit {
+	FLOW_ACTION_HW_STATS_DISABLED_BIT,
 	FLOW_ACTION_HW_STATS_IMMEDIATE_BIT,
 	FLOW_ACTION_HW_STATS_DELAYED_BIT,
 };
 
 enum flow_action_hw_stats {
-	FLOW_ACTION_HW_STATS_DISABLED = 0,
+	FLOW_ACTION_HW_STATS_DONT_CARE = 0,
+	FLOW_ACTION_HW_STATS_DISABLED =
+		BIT(FLOW_ACTION_HW_STATS_DISABLED_BIT),
 	FLOW_ACTION_HW_STATS_IMMEDIATE =
 		BIT(FLOW_ACTION_HW_STATS_IMMEDIATE_BIT),
 	FLOW_ACTION_HW_STATS_DELAYED = BIT(FLOW_ACTION_HW_STATS_DELAYED_BIT),
@@ -325,7 +328,11 @@ __flow_action_hw_stats_check(const struct flow_action *action,
 		return true;
 	if (!flow_action_mixed_hw_stats_check(action, extack))
 		return false;
+
 	action_entry = flow_action_first_entry_get(action);
+	if (action_entry->hw_stats == FLOW_ACTION_HW_STATS_DONT_CARE)
+		return true;
+
 	if (!check_allow_bit &&
 	    action_entry->hw_stats != FLOW_ACTION_HW_STATS_ANY) {
 		NL_SET_ERR_MSG_MOD(extack, "Driver supports only default HW stats type \"any\"");
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 55bd1429678f..8ddc16a1ca68 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3523,16 +3523,27 @@ static void tcf_sample_get_group(struct flow_action_entry *entry,
 #endif
 }
 
+static enum flow_action_hw_stats tc_act_hw_stats_array[] = {
+	[0]				= FLOW_ACTION_HW_STATS_DISABLED,
+	[TCA_ACT_HW_STATS_IMMEDIATE]	= FLOW_ACTION_HW_STATS_IMMEDIATE,
+	[TCA_ACT_HW_STATS_DELAYED]	= FLOW_ACTION_HW_STATS_DELAYED,
+	[TCA_ACT_HW_STATS_ANY]		= FLOW_ACTION_HW_STATS_ANY,
+};
+
+static enum flow_action_hw_stats tc_act_hw_stats(u8 hw_stats)
+{
+	if (WARN_ON_ONCE(hw_stats > TCA_ACT_HW_STATS_ANY))
+		return FLOW_ACTION_HW_STATS_DONT_CARE;
+
+	return tc_act_hw_stats_array[hw_stats];
+}
+
 int tc_setup_flow_action(struct flow_action *flow_action,
 			 const struct tcf_exts *exts)
 {
 	struct tc_action *act;
 	int i, j, k, err = 0;
 
-	BUILD_BUG_ON(TCA_ACT_HW_STATS_ANY != FLOW_ACTION_HW_STATS_ANY);
-	BUILD_BUG_ON(TCA_ACT_HW_STATS_IMMEDIATE != FLOW_ACTION_HW_STATS_IMMEDIATE);
-	BUILD_BUG_ON(TCA_ACT_HW_STATS_DELAYED != FLOW_ACTION_HW_STATS_DELAYED);
-
 	if (!exts)
 		return 0;
 
@@ -3546,7 +3557,7 @@ int tc_setup_flow_action(struct flow_action *flow_action,
 		if (err)
 			goto err_out_locked;
 
-		entry->hw_stats = act->hw_stats;
+		entry->hw_stats = tc_act_hw_stats(act->hw_stats);
 
 		if (is_tcf_gact_ok(act)) {
 			entry->id = FLOW_ACTION_ACCEPT;
@@ -3614,7 +3625,7 @@ int tc_setup_flow_action(struct flow_action *flow_action,
 				entry->mangle.mask = tcf_pedit_mask(act, k);
 				entry->mangle.val = tcf_pedit_val(act, k);
 				entry->mangle.offset = tcf_pedit_offset(act, k);
-				entry->hw_stats = act->hw_stats;
+				entry->hw_stats = tc_act_hw_stats(act->hw_stats);
 				entry = &flow_action->entries[++j];
 			}
 		} else if (is_tcf_csum(act)) {
-- 
2.20.1