[PATCH nf,v3] netfilter: flowtable: generalize pending status bit

[PATCH nf,v3] netfilter: flowtable: generalize pending status bit

[Pablo Neira Ayuso]

Rename NF_FLOW_HW_PENDING to NF_FLOW_PENDING and use it to inhibit the
flowtable GC worker until pending offload work has been completed.

Apparently, nf_flow_offload_stats() can schedule work to retrieve stats
while the flow is being removed by GC.

And this bit can also be used in a follow up patch to disable GC until
the flow has been fully added in both directions.

Fixes: 2c8897953f3b ("netfilter: flowtable: Add pending bit for offload work")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
v3: just a rebase on top of net.git

 include/net/netfilter/nf_flow_table.h | 2 +-
 net/netfilter/nf_flow_table_core.c    | 7 ++++++-
 net/netfilter/nf_flow_table_offload.c | 6 +++---
 net/sched/act_ct.c                    | 2 +-
 4 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index f2e2771f188f..f14fd70e8289 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -186,7 +186,7 @@ enum nf_flow_flags {
 	NF_FLOW_HW,
 	NF_FLOW_HW_DYING,
 	NF_FLOW_HW_DEAD,
-	NF_FLOW_HW_PENDING,
+	NF_FLOW_PENDING,
 	NF_FLOW_HW_BIDIRECTIONAL,
 	NF_FLOW_HW_ESTABLISHED,
 };
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 934c6151f558..36bbc7be2f74 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -575,7 +575,12 @@ static void nf_flow_table_extend_ct_timeout(struct nf_conn *ct)
 static void nf_flow_offload_gc_step(struct nf_flowtable *flow_table,
 				    struct flow_offload *flow, void *data)
 {
-	bool teardown = test_bit(NF_FLOW_TEARDOWN, &flow->flags);
+	bool teardown;
+
+	if (test_bit(NF_FLOW_PENDING, &flow->flags))
+		return;
+
+	teardown = test_bit(NF_FLOW_TEARDOWN, &flow->flags);
 
 	if (nf_flow_has_expired(flow) ||
 	    nf_ct_is_dying(flow->ct) ||
diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
index 6757fd89c1f1..4d1de88ce5d5 100644
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -1057,7 +1057,7 @@ static void flow_offload_work_handler(struct work_struct *work)
 			WARN_ON_ONCE(1);
 	}
 
-	clear_bit(NF_FLOW_HW_PENDING, &offload->flow->flags);
+	clear_bit(NF_FLOW_PENDING, &offload->flow->flags);
 	if (offload->cmd == FLOW_CLS_DESTROY) {
 		/* Publish after the worker's last flow access. */
 		smp_mb__before_atomic();
@@ -1089,12 +1089,12 @@ nf_flow_offload_work_alloc(struct nf_flowtable *flowtable,
 {
 	struct flow_offload_work *offload;
 
-	if (test_and_set_bit(NF_FLOW_HW_PENDING, &flow->flags))
+	if (test_and_set_bit(NF_FLOW_PENDING, &flow->flags))
 		return NULL;
 
 	offload = kmalloc_obj(struct flow_offload_work, GFP_ATOMIC);
 	if (!offload) {
-		clear_bit(NF_FLOW_HW_PENDING, &flow->flags);
+		clear_bit(NF_FLOW_PENDING, &flow->flags);
 		return NULL;
 	}
 
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 9080cb386c16..97d38608a451 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -289,7 +289,7 @@ static bool tcf_ct_flow_is_outdated(const struct flow_offload *flow)
 {
 	return test_bit(IPS_SEEN_REPLY_BIT, &flow->ct->status) &&
 	       test_bit(IPS_HW_OFFLOAD_BIT, &flow->ct->status) &&
-	       !test_bit(NF_FLOW_HW_PENDING, &flow->flags) &&
+	       !test_bit(NF_FLOW_PENDING, &flow->flags) &&
 	       !test_bit(NF_FLOW_HW_ESTABLISHED, &flow->flags);
 }
 
-- 
2.47.3