Merge branch 'netlink-formatted-extacks'

Edward Cree says:

====================
netlink: formatted extacks

Currently, netlink extacks can only carry fixed string messages, which
 is limiting when reporting failures in complex systems.  This series
 adds the ability to return printf-formatted messages, and uses it in
 the sfc driver's TC offload code.
Formatted extack messages are limited in length to a fixed buffer size,
 currently 80 characters.  If the message exceeds this, the full message
 will be logged (ratelimited) to the console and a truncated version
 returned over netlink.
There is no change to the netlink uAPI; only internal kernel changes
 are needed.
====================

Link: https://lore.kernel.org/r/cover.1666102698.git.ecree.xilinx@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

8 files changed, 50 insertions, 92 deletions

diff --git a/drivers/net/ethernet/sfc/ef100_ethtool.c b/drivers/net/ethernet/sfc/ef100_ethtool.c
index 135ece2f1375..702abbe59b76 100644
--- a/drivers/net/ethernet/sfc/ef100_ethtool.c
+++ b/drivers/net/ethernet/sfc/ef100_ethtool.c
@@ -43,8 +43,6 @@ const struct ethtool_ops ef100_ethtool_ops = {
 	.get_pauseparam         = efx_ethtool_get_pauseparam,
 	.set_pauseparam         = efx_ethtool_set_pauseparam,
 	.get_sset_count		= efx_ethtool_get_sset_count,
-	.get_priv_flags		= efx_ethtool_get_priv_flags,
-	.set_priv_flags		= efx_ethtool_set_priv_flags,
 	.self_test		= efx_ethtool_self_test,
 	.get_strings		= efx_ethtool_get_strings,
 	.get_link_ksettings	= efx_ethtool_get_link_ksettings,
diff --git a/drivers/net/ethernet/sfc/ethtool_common.c b/drivers/net/ethernet/sfc/ethtool_common.c
index 6649a2327d03..a8cbceeb301b 100644
--- a/drivers/net/ethernet/sfc/ethtool_common.c
+++ b/drivers/net/ethernet/sfc/ethtool_common.c
@@ -101,14 +101,6 @@ static const struct efx_sw_stat_desc efx_sw_stat_desc[] = {
 
 #define EFX_ETHTOOL_SW_STAT_COUNT ARRAY_SIZE(efx_sw_stat_desc)
 
-static const char efx_ethtool_priv_flags_strings[][ETH_GSTRING_LEN] = {
-	"log-tc-errors",
-};
-
-#define EFX_ETHTOOL_PRIV_FLAGS_LOG_TC_ERRS		BIT(0)
-
-#define EFX_ETHTOOL_PRIV_FLAGS_COUNT ARRAY_SIZE(efx_ethtool_priv_flags_strings)
-
 void efx_ethtool_get_drvinfo(struct net_device *net_dev,
 			     struct ethtool_drvinfo *info)
 {
@@ -460,8 +452,6 @@ int efx_ethtool_get_sset_count(struct net_device *net_dev, int string_set)
 		       efx_ptp_describe_stats(efx, NULL);
 	case ETH_SS_TEST:
 		return efx_ethtool_fill_self_tests(efx, NULL, NULL, NULL);
-	case ETH_SS_PRIV_FLAGS:
-		return EFX_ETHTOOL_PRIV_FLAGS_COUNT;
 	default:
 		return -EINVAL;
 	}
@@ -488,39 +478,12 @@ void efx_ethtool_get_strings(struct net_device *net_dev,
 	case ETH_SS_TEST:
 		efx_ethtool_fill_self_tests(efx, NULL, strings, NULL);
 		break;
-	case ETH_SS_PRIV_FLAGS:
-		for (i = 0; i < EFX_ETHTOOL_PRIV_FLAGS_COUNT; i++)
-			strscpy(strings + i * ETH_GSTRING_LEN,
-				efx_ethtool_priv_flags_strings[i],
-				ETH_GSTRING_LEN);
-		break;
 	default:
 		/* No other string sets */
 		break;
 	}
 }
 
-u32 efx_ethtool_get_priv_flags(struct net_device *net_dev)
-{
-	struct efx_nic *efx = efx_netdev_priv(net_dev);
-	u32 ret_flags = 0;
-
-	if (efx->log_tc_errs)
-		ret_flags |= EFX_ETHTOOL_PRIV_FLAGS_LOG_TC_ERRS;
-
-	return ret_flags;
-}
-
-int efx_ethtool_set_priv_flags(struct net_device *net_dev, u32 flags)
-{
-	struct efx_nic *efx = efx_netdev_priv(net_dev);
-
-	efx->log_tc_errs =
-		!!(flags & EFX_ETHTOOL_PRIV_FLAGS_LOG_TC_ERRS);
-
-	return 0;
-}
-
 void efx_ethtool_get_stats(struct net_device *net_dev,
 			   struct ethtool_stats *stats,
 			   u64 *data)
diff --git a/drivers/net/ethernet/sfc/ethtool_common.h b/drivers/net/ethernet/sfc/ethtool_common.h
index 0afc74021a5e..659491932101 100644
--- a/drivers/net/ethernet/sfc/ethtool_common.h
+++ b/drivers/net/ethernet/sfc/ethtool_common.h
@@ -27,8 +27,6 @@ int efx_ethtool_fill_self_tests(struct efx_nic *efx,
 int efx_ethtool_get_sset_count(struct net_device *net_dev, int string_set);
 void efx_ethtool_get_strings(struct net_device *net_dev, u32 string_set,
 			     u8 *strings);
-u32 efx_ethtool_get_priv_flags(struct net_device *net_dev);
-int efx_ethtool_set_priv_flags(struct net_device *net_dev, u32 flags);
 void efx_ethtool_get_stats(struct net_device *net_dev,
 			   struct ethtool_stats *stats __attribute__ ((unused)),
 			   u64 *data);
diff --git a/drivers/net/ethernet/sfc/mae.c b/drivers/net/ethernet/sfc/mae.c
index 874c765b2465..6f472ea0638a 100644
--- a/drivers/net/ethernet/sfc/mae.c
+++ b/drivers/net/ethernet/sfc/mae.c
@@ -265,9 +265,8 @@ int efx_mae_match_check_caps(struct efx_nic *efx,
 	rc = efx_mae_match_check_cap_typ(supported_fields[MAE_FIELD_INGRESS_PORT],
 					 ingress_port_mask_type);
 	if (rc) {
-		efx_tc_err(efx, "No support for %s mask in field ingress_port\n",
-			   mask_type_name(ingress_port_mask_type));
-		NL_SET_ERR_MSG_MOD(extack, "Unsupported mask type for ingress_port");
+		NL_SET_ERR_MSG_FMT_MOD(extack, "No support for %s mask in field ingress_port",
+				       mask_type_name(ingress_port_mask_type));
 		return rc;
 	}
 	return 0;
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 2e9ba0cfe848..7ef823d7a89a 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -855,7 +855,6 @@ enum efx_xdp_tx_queues_mode {
  * @timer_max_ns: Interrupt timer maximum value, in nanoseconds
  * @irq_rx_adaptive: Adaptive IRQ moderation enabled for RX event queues
  * @irqs_hooked: Channel interrupts are hooked
- * @log_tc_errs: Error logging for TC filter insertion is enabled
  * @irq_rx_mod_step_us: Step size for IRQ moderation for RX event queues
  * @irq_rx_moderation_us: IRQ moderation time for RX event queues
  * @msg_enable: Log message enable flags
@@ -1018,7 +1017,6 @@ struct efx_nic {
 	unsigned int timer_max_ns;
 	bool irq_rx_adaptive;
 	bool irqs_hooked;
-	bool log_tc_errs;
 	unsigned int irq_mod_step_us;
 	unsigned int irq_rx_moderation_us;
 	u32 msg_enable;
diff --git a/drivers/net/ethernet/sfc/tc.c b/drivers/net/ethernet/sfc/tc.c
index 3478860d4023..b21a961eabb1 100644
--- a/drivers/net/ethernet/sfc/tc.c
+++ b/drivers/net/ethernet/sfc/tc.c
@@ -137,17 +137,16 @@ static int efx_tc_flower_parse_match(struct efx_nic *efx,
 		flow_rule_match_control(rule, &fm);
 
 		if (fm.mask->flags) {
-			efx_tc_err(efx, "Unsupported match on control.flags %#x\n",
-				   fm.mask->flags);
-			NL_SET_ERR_MSG_MOD(extack, "Unsupported match on control.flags");
+			NL_SET_ERR_MSG_FMT_MOD(extack, "Unsupported match on control.flags %#x",
+					       fm.mask->flags);
 			return -EOPNOTSUPP;
 		}
 	}
 	if (dissector->used_keys &
 	    ~(BIT(FLOW_DISSECTOR_KEY_CONTROL) |
 	      BIT(FLOW_DISSECTOR_KEY_BASIC))) {
-		efx_tc_err(efx, "Unsupported flower keys %#x\n", dissector->used_keys);
-		NL_SET_ERR_MSG_MOD(extack, "Unsupported flower keys encountered");
+		NL_SET_ERR_MSG_FMT_MOD(extack, "Unsupported flower keys %#x",
+				       dissector->used_keys);
 		return -EOPNOTSUPP;
 	}
 
@@ -156,11 +155,11 @@ static int efx_tc_flower_parse_match(struct efx_nic *efx,
 
 		flow_rule_match_basic(rule, &fm);
 		if (fm.mask->n_proto) {
-			EFX_TC_ERR_MSG(efx, extack, "Unsupported eth_proto match\n");
+			NL_SET_ERR_MSG_MOD(extack, "Unsupported eth_proto match");
 			return -EOPNOTSUPP;
 		}
 		if (fm.mask->ip_proto) {
-			EFX_TC_ERR_MSG(efx, extack, "Unsupported ip_proto match\n");
+			NL_SET_ERR_MSG_MOD(extack, "Unsupported ip_proto match");
 			return -EOPNOTSUPP;
 		}
 	}
@@ -200,13 +199,9 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 
 	if (efv != from_efv) {
 		/* can't happen */
-		efx_tc_err(efx, "for %s efv is %snull but from_efv is %snull\n",
-			   netdev_name(net_dev), efv ? "non-" : "",
-			   from_efv ? "non-" : "");
-		if (efv)
-			NL_SET_ERR_MSG_MOD(extack, "vfrep filter has PF net_dev (can't happen)");
-		else
-			NL_SET_ERR_MSG_MOD(extack, "PF filter has vfrep net_dev (can't happen)");
+		NL_SET_ERR_MSG_FMT_MOD(extack, "for %s efv is %snull but from_efv is %snull (can't happen)",
+				       netdev_name(net_dev), efv ? "non-" : "",
+				       from_efv ? "non-" : "");
 		return -EINVAL;
 	}
 
@@ -214,7 +209,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 	memset(&match, 0, sizeof(match));
 	rc = efx_tc_flower_external_mport(efx, from_efv);
 	if (rc < 0) {
-		EFX_TC_ERR_MSG(efx, extack, "Failed to identify ingress m-port");
+		NL_SET_ERR_MSG_MOD(extack, "Failed to identify ingress m-port");
 		return rc;
 	}
 	match.value.ingress_port = rc;
@@ -224,7 +219,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 		return rc;
 
 	if (tc->common.chain_index) {
-		EFX_TC_ERR_MSG(efx, extack, "No support for nonzero chain_index");
+		NL_SET_ERR_MSG_MOD(extack, "No support for nonzero chain_index");
 		return -EOPNOTSUPP;
 	}
 	match.mask.recirc_id = 0xff;
@@ -261,7 +256,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 
 		if (!act) {
 			/* more actions after a non-pipe action */
-			EFX_TC_ERR_MSG(efx, extack, "Action follows non-pipe action");
+			NL_SET_ERR_MSG_MOD(extack, "Action follows non-pipe action");
 			rc = -EINVAL;
 			goto release;
 		}
@@ -270,7 +265,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 		case FLOW_ACTION_DROP:
 			rc = efx_mae_alloc_action_set(efx, act);
 			if (rc) {
-				EFX_TC_ERR_MSG(efx, extack, "Failed to write action set to hw (drop)");
+				NL_SET_ERR_MSG_MOD(extack, "Failed to write action set to hw (drop)");
 				goto release;
 			}
 			list_add_tail(&act->list, &rule->acts.list);
@@ -281,20 +276,20 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 			save = *act;
 			to_efv = efx_tc_flower_lookup_efv(efx, fa->dev);
 			if (IS_ERR(to_efv)) {
-				EFX_TC_ERR_MSG(efx, extack, "Mirred egress device not on switch");
+				NL_SET_ERR_MSG_MOD(extack, "Mirred egress device not on switch");
 				rc = PTR_ERR(to_efv);
 				goto release;
 			}
 			rc = efx_tc_flower_external_mport(efx, to_efv);
 			if (rc < 0) {
-				EFX_TC_ERR_MSG(efx, extack, "Failed to identify egress m-port");
+				NL_SET_ERR_MSG_MOD(extack, "Failed to identify egress m-port");
 				goto release;
 			}
 			act->dest_mport = rc;
 			act->deliver = 1;
 			rc = efx_mae_alloc_action_set(efx, act);
 			if (rc) {
-				EFX_TC_ERR_MSG(efx, extack, "Failed to write action set to hw (mirred)");
+				NL_SET_ERR_MSG_MOD(extack, "Failed to write action set to hw (mirred)");
 				goto release;
 			}
 			list_add_tail(&act->list, &rule->acts.list);
@@ -310,9 +305,9 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 			*act = save;
 			break;
 		default:
-			efx_tc_err(efx, "Unhandled action %u\n", fa->id);
+			NL_SET_ERR_MSG_FMT_MOD(extack, "Unhandled action %u",
+					       fa->id);
 			rc = -EOPNOTSUPP;
-			NL_SET_ERR_MSG_MOD(extack, "Unsupported action");
 			goto release;
 		}
 	}
@@ -334,7 +329,7 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 		act->deliver = 1;
 		rc = efx_mae_alloc_action_set(efx, act);
 		if (rc) {
-			EFX_TC_ERR_MSG(efx, extack, "Failed to write action set to hw (deliver)");
+			NL_SET_ERR_MSG_MOD(extack, "Failed to write action set to hw (deliver)");
 			goto release;
 		}
 		list_add_tail(&act->list, &rule->acts.list);
@@ -349,13 +344,13 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 
 	rc = efx_mae_alloc_action_set_list(efx, &rule->acts);
 	if (rc) {
-		EFX_TC_ERR_MSG(efx, extack, "Failed to write action set list to hw");
+		NL_SET_ERR_MSG_MOD(extack, "Failed to write action set list to hw");
 		goto release;
 	}
 	rc = efx_mae_insert_rule(efx, &rule->match, EFX_TC_PRIO_TC,
 				 rule->acts.fw_id, &rule->fw_id);
 	if (rc) {
-		EFX_TC_ERR_MSG(efx, extack, "Failed to insert rule in hw");
+		NL_SET_ERR_MSG_MOD(extack, "Failed to insert rule in hw");
 		goto release_acts;
 	}
 	return 0;
diff --git a/drivers/net/ethernet/sfc/tc.h b/drivers/net/ethernet/sfc/tc.h
index 196fd74ed973..4373c3243e3c 100644
--- a/drivers/net/ethernet/sfc/tc.h
+++ b/drivers/net/ethernet/sfc/tc.h
@@ -15,24 +15,6 @@
 #include <linux/rhashtable.h>
 #include "net_driver.h"
 
-/* Error reporting: convenience macros.  For indicating why a given filter
- * insertion is not supported; errors in internal operation or in the
- * hardware should be netif_err()s instead.
- */
-/* Used when error message is constant. */
-#define EFX_TC_ERR_MSG(efx, extack, message)	do {			\
-	NL_SET_ERR_MSG_MOD(extack, message);				\
-	if (efx->log_tc_errs)						\
-		netif_info(efx, drv, efx->net_dev, "%s\n", message);	\
-} while (0)
-/* Used when error message is not constant; caller should also supply a
- * constant extack message with NL_SET_ERR_MSG_MOD().
- */
-#define efx_tc_err(efx, fmt, args...)	do {		\
-if (efx->log_tc_errs)					\
-	netif_info(efx, drv, efx->net_dev, fmt, ##args);\
-} while (0)
-
 struct efx_tc_action_set {
 	u16 deliver:1;
 	u32 dest_mport;
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index d51e041d2242..d81bde5a5844 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -64,6 +64,7 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
 
 /* this can be increased when necessary - don't expose to userland */
 #define NETLINK_MAX_COOKIE_LEN	20
+#define NETLINK_MAX_FMTMSG_LEN	80
 
 /**
  * struct netlink_ext_ack - netlink extended ACK report struct
@@ -75,6 +76,8 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
  * @miss_nest: nest missing an attribute (%NULL if missing top level attr)
  * @cookie: cookie data to return to userspace (for success)
  * @cookie_len: actual cookie data length
+ * @_msg_buf: output buffer for formatted message strings - don't access
+ *	directly, use %NL_SET_ERR_MSG_FMT
  */
 struct netlink_ext_ack {
 	const char *_msg;
@@ -84,13 +87,13 @@ struct netlink_ext_ack {
 	u16 miss_type;
 	u8 cookie[NETLINK_MAX_COOKIE_LEN];
 	u8 cookie_len;
+	char _msg_buf[NETLINK_MAX_FMTMSG_LEN];
 };
 
 /* Always use this macro, this allows later putting the
  * message into a separate section or such for things
  * like translation or listing all possible messages.
- * Currently string formatting is not supported (due
- * to the lack of an output buffer.)
+ * If string formatting is needed use NL_SET_ERR_MSG_FMT.
  */
 #define NL_SET_ERR_MSG(extack, msg) do {		\
 	static const char __msg[] = msg;		\
@@ -102,9 +105,31 @@ struct netlink_ext_ack {
 		__extack->_msg = __msg;			\
 } while (0)
 
+/* We splice fmt with %s at each end even in the snprintf so that both calls
+ * can use the same string constant, avoiding its duplication in .ro
+ */
+#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do {			       \
+	struct netlink_ext_ack *__extack = (extack);			       \
+									       \
+	if (!__extack)							       \
+		break;							       \
+	if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN,	       \
+		     "%s" fmt "%s", "", ##args, "") >=			       \
+	    NETLINK_MAX_FMTMSG_LEN)					       \
+		net_warn_ratelimited("%s" fmt "%s", "truncated extack: ",      \
+				     ##args, "\n");			       \
+									       \
+	do_trace_netlink_extack(__extack->_msg_buf);			       \
+									       \
+	__extack->_msg = __extack->_msg_buf;				       \
+} while (0)
+
 #define NL_SET_ERR_MSG_MOD(extack, msg)			\
 	NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
 
+#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...)	\
+	NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
+
 #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {	\
 	if ((extack)) {					\
 		(extack)->bad_attr = (attr);		\