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

[Jiri Pirko <jiri@resnulli.us>]

Tue, May 05, 2020 at 11:21:59AM CEST, pablo@netfilter.org wrote:
>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,

TCA_ACT_HW_* are bits. There can be a combination of those according
to the user request. For 2 bits, it is not problem, but I have a
patchset in pipes adding another type.
Then you need to have 1:1 mapping in this array for all bit
combinations. That is not right.

How about putting DISABLED to the at the end of enum
flow_action_hw_stats? They you can just map 0 here to FLOW_ACTION_HW_STATS_DISABLED
as an exception, but the bits you can take 1:1.



>+};
>+
>+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
>