[PATCH net,v2] 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.

TCA_ACT_HW_STATS_* maintains the 1:1 mapping with FLOW_ACTION_HW_STATS_*
except by disabled which is mapped to FLOW_ACTION_HW_STATS_DISABLED
(this is 0 in tc). 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>
---
v2: define FLOW_ACTION_HW_STATS_DISABLED at the end of the enumeration
    as Jiri suggested. Keep the 1:1 mapping between TCA_ACT_HW_STATS_*
    and FLOW_ACTION_HW_STATS_* except by the disabled case.

 include/net/flow_offload.h |  9 ++++++++-
 net/sched/cls_api.c        | 14 ++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
index 3619c6acf60f..efc8350b42fb 100644
--- a/include/net/flow_offload.h
+++ b/include/net/flow_offload.h
@@ -166,15 +166,18 @@ enum flow_action_mangle_base {
 enum flow_action_hw_stats_bit {
 	FLOW_ACTION_HW_STATS_IMMEDIATE_BIT,
 	FLOW_ACTION_HW_STATS_DELAYED_BIT,
+	FLOW_ACTION_HW_STATS_DISABLED_BIT,
 };
 
 enum flow_action_hw_stats {
-	FLOW_ACTION_HW_STATS_DISABLED = 0,
+	FLOW_ACTION_HW_STATS_DONT_CARE = 0,
 	FLOW_ACTION_HW_STATS_IMMEDIATE =
 		BIT(FLOW_ACTION_HW_STATS_IMMEDIATE_BIT),
 	FLOW_ACTION_HW_STATS_DELAYED = BIT(FLOW_ACTION_HW_STATS_DELAYED_BIT),
 	FLOW_ACTION_HW_STATS_ANY = FLOW_ACTION_HW_STATS_IMMEDIATE |
 				   FLOW_ACTION_HW_STATS_DELAYED,
+	FLOW_ACTION_HW_STATS_DISABLED =
+		BIT(FLOW_ACTION_HW_STATS_DISABLED_BIT),
 };
 
 typedef void (*action_destr)(void *priv);
@@ -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..56cf1b9e1e24 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3523,6 +3523,16 @@ static void tcf_sample_get_group(struct flow_action_entry *entry,
 #endif
 }
 
+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;
+	else if (!hw_stats)
+		return FLOW_ACTION_HW_STATS_DISABLED;
+
+	return hw_stats;
+}
+
 int tc_setup_flow_action(struct flow_action *flow_action,
 			 const struct tcf_exts *exts)
 {
@@ -3546,7 +3556,7 @@ 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 +3624,7 @@ 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