cxgb4: check rule prio conflicts before offload

Only offload rule if it satisfies both of the following conditions:
1. The immediate previous rule has priority <= current rule's priority.
2. The immediate next rule has priority >= current rule's priority.

Also rework free entry fetch logic to search from end of TCAM, instead
of beginning, because higher indices have lower priority than lower
indices. This is similar to how TC auto generates priority values.

v5:
- Fixed commit message and comment to include comparison for equal
  priority.

v4:
- Patch added in this version.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -1286,8 +1286,11 @@ struct ch_filter_specification {
 	u16 nat_lport;		/* local port to use after NAT'ing */
 	u16 nat_fport;		/* foreign port to use after NAT'ing */
 
+	u32 tc_prio;		/* TC's filter priority index */
+	u64 tc_cookie;		/* Unique cookie identifying TC rules */
+
 	/* reservation for future additions */
-	u8 rsvd[24];
+	u8 rsvd[12];
 
 	/* Filter rule value/mask pairs.
 	 */

drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.c

@@ -440,36 +440,48 @@ int cxgb4_get_free_ftid(struct net_device *dev, int family)
 {
 	struct adapter *adap = netdev2adap(dev);
 	struct tid_info *t = &adap->tids;
+	bool found = false;
+	u8 i, n, cnt;
 	int ftid;
 
-	spin_lock_bh(&t->ftid_lock);
-	if (family == PF_INET) {
-		ftid = find_first_zero_bit(t->ftid_bmap, t->nftids);
-		if (ftid >= t->nftids)
-			ftid = -1;
-	} else {
-		if (is_t6(adap->params.chip)) {
-			ftid = bitmap_find_free_region(t->ftid_bmap,
-						       t->nftids, 1);
-			if (ftid < 0)
-				goto out_unlock;
-
-			/* this is only a lookup, keep the found region
-			 * unallocated
+	/* IPv4 occupy 1 slot. IPv6 occupy 2 slots on T6 and 4 slots
+	 * on T5.
 	 */
-			bitmap_release_region(t->ftid_bmap, ftid, 1);
-		} else {
-			ftid = bitmap_find_free_region(t->ftid_bmap,
-						       t->nftids, 2);
-			if (ftid < 0)
-				goto out_unlock;
+	n = 1;
+	if (family == PF_INET6) {
+		n++;
+		if (CHELSIO_CHIP_VERSION(adap->params.chip) < CHELSIO_T6)
+			n += 2;
+	}
+
+	if (n > t->nftids)
+		return -ENOMEM;
 
-			bitmap_release_region(t->ftid_bmap, ftid, 2);
+	/* Find free filter slots from the end of TCAM. Appropriate
+	 * checks must be done by caller later to ensure the prio
+	 * passed by TC doesn't conflict with prio saved by existing
+	 * rules in the TCAM.
+	 */
+	spin_lock_bh(&t->ftid_lock);
+	ftid = t->nftids - 1;
+	while (ftid >= n - 1) {
+		cnt = 0;
+		for (i = 0; i < n; i++) {
+			if (test_bit(ftid - i, t->ftid_bmap))
+				break;
+			cnt++;
+		}
+		if (cnt == n) {
+			ftid &= ~(n - 1);
+			found = true;
+			break;
 		}
+
+		ftid -= n;
 	}
-out_unlock:
 	spin_unlock_bh(&t->ftid_lock);
-	return ftid;
+
+	return found ? ftid : -ENOMEM;
 }
 
 static int cxgb4_set_ftid(struct tid_info *t, int fidx, int family,
@@ -510,6 +522,60 @@ static void cxgb4_clear_ftid(struct tid_info *t, int fidx, int family,
 	spin_unlock_bh(&t->ftid_lock);
 }
 
+bool cxgb4_filter_prio_in_range(struct net_device *dev, u32 idx, u32 prio)
+{
+	struct adapter *adap = netdev2adap(dev);
+	struct filter_entry *prev_fe, *next_fe;
+	struct tid_info *t = &adap->tids;
+	u32 prev_ftid, next_ftid;
+	bool valid = true;
+
+	/* Only insert the rule if both of the following conditions
+	 * are met:
+	 * 1. The immediate previous rule has priority <= @prio.
+	 * 2. The immediate next rule has priority >= @prio.
+	 */
+	spin_lock_bh(&t->ftid_lock);
+	/* Don't insert if there's a rule already present at @idx. */
+	if (test_bit(idx, t->ftid_bmap)) {
+		valid = false;
+		goto out_unlock;
+	}
+
+	next_ftid = find_next_bit(t->ftid_bmap, t->nftids, idx);
+	if (next_ftid >= t->nftids)
+		next_ftid = idx;
+
+	next_fe = &adap->tids.ftid_tab[next_ftid];
+
+	prev_ftid = find_last_bit(t->ftid_bmap, idx);
+	if (prev_ftid >= idx)
+		prev_ftid = idx;
+
+	/* See if the filter entry belongs to an IPv6 rule, which
+	 * occupy 4 slots on T5 and 2 slots on T6. Adjust the
+	 * reference to the previously inserted filter entry
+	 * accordingly.
+	 */
+	if (CHELSIO_CHIP_VERSION(adap->params.chip) < CHELSIO_T6) {
+		prev_fe = &adap->tids.ftid_tab[prev_ftid & ~0x3];
+		if (!prev_fe->fs.type)
+			prev_fe = &adap->tids.ftid_tab[prev_ftid];
+	} else {
+		prev_fe = &adap->tids.ftid_tab[prev_ftid & ~0x1];
+		if (!prev_fe->fs.type)
+			prev_fe = &adap->tids.ftid_tab[prev_ftid];
+	}
+
+	if ((prev_fe->valid && prio < prev_fe->fs.tc_prio) ||
+	    (next_fe->valid && prio > next_fe->fs.tc_prio))
+		valid = false;
+
+out_unlock:
+	spin_unlock_bh(&t->ftid_lock);
+	return valid;
+}
+
 /* Delete the filter at a specified index. */
 static int del_filter_wr(struct adapter *adapter, int fidx)
 {

drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.h

@@ -53,4 +53,5 @@ void clear_all_filters(struct adapter *adapter);
 void init_hash_filter(struct adapter *adap);
 bool is_filter_exact_match(struct adapter *adap,
 			   struct ch_filter_specification *fs);
+bool cxgb4_filter_prio_in_range(struct net_device *dev, u32 idx, u32 prio);
 #endif /* __CXGB4_FILTER_H */

drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_flower.c

@@ -636,12 +636,12 @@ static int cxgb4_validate_flow_actions(struct net_device *dev,
 int cxgb4_tc_flower_replace(struct net_device *dev,
 			    struct flow_cls_offload *cls)
 {
+	struct netlink_ext_ack *extack = cls->common.extack;
 	struct adapter *adap = netdev2adap(dev);
 	struct ch_tc_flower_entry *ch_flower;
 	struct ch_filter_specification *fs;
 	struct filter_ctx ctx;
-	int fidx;
-	int ret;
+	int fidx, ret;
 
 	if (cxgb4_validate_flow_actions(dev, cls))
 		return -EOPNOTSUPP;
@@ -664,14 +664,35 @@ int cxgb4_tc_flower_replace(struct net_device *dev,
 	if (fs->hash) {
 		fidx = 0;
 	} else {
-		fidx = cxgb4_get_free_ftid(dev, fs->type ? PF_INET6 : PF_INET);
-		if (fidx < 0) {
-			netdev_err(dev, "%s: No fidx for offload.\n", __func__);
+		u8 inet_family;
+
+		inet_family = fs->type ? PF_INET6 : PF_INET;
+
+		/* Note that TC uses prio 0 to indicate stack to
+		 * generate automatic prio and hence doesn't pass prio
+		 * 0 to driver. However, the hardware TCAM index
+		 * starts from 0. Hence, the -1 here.
+		 */
+		if (cls->common.prio <= adap->tids.nftids)
+			fidx = cls->common.prio - 1;
+		else
+			fidx = cxgb4_get_free_ftid(dev, inet_family);
+
+		/* Only insert FLOWER rule if its priority doesn't
+		 * conflict with existing rules in the LETCAM.
+		 */
+		if (fidx < 0 ||
+		    !cxgb4_filter_prio_in_range(dev, fidx, cls->common.prio)) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "No free LETCAM index available");
 			ret = -ENOMEM;
 			goto free_entry;
 		}
 	}
 
+	fs->tc_prio = cls->common.prio;
+	fs->tc_cookie = cls->cookie;
+
 	init_completion(&ctx.completion);
 	ret = __cxgb4_set_filter(dev, fidx, fs, &ctx);
 	if (ret) {

drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c

@@ -36,6 +36,7 @@
 #include <net/tc_act/tc_mirred.h>
 
 #include "cxgb4.h"
+#include "cxgb4_filter.h"
 #include "cxgb4_tc_u32_parse.h"
 #include "cxgb4_tc_u32.h"
 
@@ -148,6 +149,7 @@ static int fill_action_fields(struct adapter *adap,
 int cxgb4_config_knode(struct net_device *dev, struct tc_cls_u32_offload *cls)
 {
 	const struct cxgb4_match_field *start, *link_start = NULL;
+	struct netlink_ext_ack *extack = cls->common.extack;
 	struct adapter *adapter = netdev2adap(dev);
 	__be16 protocol = cls->common.protocol;
 	struct ch_filter_specification fs;
@@ -164,14 +166,21 @@ int cxgb4_config_knode(struct net_device *dev, struct tc_cls_u32_offload *cls)
 	if (protocol != htons(ETH_P_IP) && protocol != htons(ETH_P_IPV6))
 		return -EOPNOTSUPP;
 
-	/* Fetch the location to insert the filter. */
-	filter_id = cls->knode.handle & 0xFFFFF;
+	/* Note that TC uses prio 0 to indicate stack to generate
+	 * automatic prio and hence doesn't pass prio 0 to driver.
+	 * However, the hardware TCAM index starts from 0. Hence, the
+	 * -1 here.
+	 */
+	filter_id = TC_U32_NODE(cls->knode.handle) - 1;
 
-	if (filter_id > adapter->tids.nftids) {
-		dev_err(adapter->pdev_dev,
-			"Location %d out of range for insertion. Max: %d\n",
-			filter_id, adapter->tids.nftids);
-		return -ERANGE;
+	/* Only insert U32 rule if its priority doesn't conflict with
+	 * existing rules in the LETCAM.
+	 */
+	if (filter_id >= adapter->tids.nftids ||
+	    !cxgb4_filter_prio_in_range(dev, filter_id, cls->common.prio)) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "No free LETCAM index available");
+		return -ENOMEM;
 	}
 
 	t = adapter->tc_u32;
@@ -190,6 +199,9 @@ int cxgb4_config_knode(struct net_device *dev, struct tc_cls_u32_offload *cls)
 
 	memset(&fs, 0, sizeof(fs));
 
+	fs.tc_prio = cls->common.prio;
+	fs.tc_cookie = cls->knode.handle;
+
 	if (protocol == htons(ETH_P_IPV6)) {
 		start = cxgb4_ipv6_fields;
 		is_ipv6 = true;
@@ -350,14 +362,10 @@ int cxgb4_delete_knode(struct net_device *dev, struct tc_cls_u32_offload *cls)
 		return -EOPNOTSUPP;
 
 	/* Fetch the location to delete the filter. */
-	filter_id = cls->knode.handle & 0xFFFFF;
-
-	if (filter_id > adapter->tids.nftids) {
-		dev_err(adapter->pdev_dev,
-			"Location %d out of range for deletion. Max: %d\n",
-			filter_id, adapter->tids.nftids);
+	filter_id = TC_U32_NODE(cls->knode.handle) - 1;
+	if (filter_id >= adapter->tids.nftids ||
+	    cls->knode.handle != adapter->tids.ftid_tab[filter_id].fs.tc_cookie)
 		return -ERANGE;
-	}
 
 	t = adapter->tc_u32;
 	handle = cls->knode.handle;