[PATCH net-next 27/35] rxrpc: Simplify skbuff accounting in receive path
From: David Howells
Date: Wed Nov 30 2022 - 12:02:56 EST
A received skbuff needs a ref when it gets put on a call data queue or conn
packet queue, and rxrpc_input_packet() and co. jump through a lot of hoops
to avoid double-dropping the skbuff ref so that we can avoid getting a ref
when we queue the packet.
Change this so that the skbuff ref is unconditionally dropped by the caller
of rxrpc_input_packet(). An additional ref is then taken on the packet if
it is pushed onto a queue.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
---
include/trace/events/rxrpc.h | 3 +-
net/rxrpc/input.c | 45 +++++++++++++--------------
net/rxrpc/io_thread.c | 70 +++++++++++++++++++-----------------------
3 files changed, 56 insertions(+), 62 deletions(-)
diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index c3043fbea0e6..82b1327c2ba6 100644
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -28,6 +28,8 @@
EM(rxrpc_skb_eaten_by_unshare_nomem, "ETN unshar-nm") \
EM(rxrpc_skb_get_ack, "GET ack ") \
EM(rxrpc_skb_get_conn_work, "GET conn-work") \
+ EM(rxrpc_skb_get_local_work, "GET locl-work") \
+ EM(rxrpc_skb_get_reject_work, "GET rej-work ") \
EM(rxrpc_skb_get_to_recvmsg, "GET to-recv ") \
EM(rxrpc_skb_get_to_recvmsg_oos, "GET to-recv-o") \
EM(rxrpc_skb_new_encap_rcv, "NEW encap-rcv") \
@@ -39,7 +41,6 @@
EM(rxrpc_skb_put_error_report, "PUT error-rep") \
EM(rxrpc_skb_put_input, "PUT input ") \
EM(rxrpc_skb_put_jumbo_subpacket, "PUT jumbo-sub") \
- EM(rxrpc_skb_put_lose, "PUT lose ") \
EM(rxrpc_skb_put_purge, "PUT purge ") \
EM(rxrpc_skb_put_rotate, "PUT rotate ") \
EM(rxrpc_skb_put_unknown, "PUT unknown ") \
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 036f02371051..42addbcf59f9 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -338,7 +338,8 @@ static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb,
/*
* Process a DATA packet.
*/
-static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
+static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,
+ bool *_notify)
{
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct sk_buff *oos;
@@ -361,7 +362,7 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
if (test_and_set_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
seq + 1 != wtop) {
rxrpc_proto_abort("LSN", call, seq);
- goto err_free;
+ return;
}
} else {
if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
@@ -369,7 +370,7 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
pr_warn("Packet beyond last: c=%x q=%x window=%x-%x wlimit=%x\n",
call->debug_id, seq, window, wtop, wlimit);
rxrpc_proto_abort("LSA", call, seq);
- goto err_free;
+ return;
}
}
@@ -402,9 +403,11 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
if (after(window, wtop))
wtop = window;
+ rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg);
+
spin_lock(&call->recvmsg_queue.lock);
rxrpc_input_queue_data(call, skb, window, wtop, rxrpc_receive_queue);
- skb = NULL;
+ *_notify = true;
while ((oos = skb_peek(&call->rx_oos_queue))) {
struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
@@ -456,16 +459,17 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
struct rxrpc_skb_priv *osp = rxrpc_skb(oos);
if (after(osp->hdr.seq, seq)) {
+ rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
__skb_queue_before(&call->rx_oos_queue, oos, skb);
goto oos_queued;
}
}
+ rxrpc_get_skb(skb, rxrpc_skb_get_to_recvmsg_oos);
__skb_queue_tail(&call->rx_oos_queue, skb);
oos_queued:
trace_rxrpc_receive(call, last ? rxrpc_receive_oos_last : rxrpc_receive_oos,
sp->hdr.serial, sp->hdr.seq);
- skb = NULL;
}
send_ack:
@@ -483,9 +487,6 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb)
else
rxrpc_propose_delay_ACK(call, serial,
rxrpc_propose_ack_input_data);
-
-err_free:
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
}
/*
@@ -498,6 +499,7 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb
struct sk_buff *jskb;
unsigned int offset = sizeof(struct rxrpc_wire_header);
unsigned int len = skb->len - offset;
+ bool notify = false;
while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {
if (len < RXRPC_JUMBO_SUBPKTLEN)
@@ -517,7 +519,8 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb
jsp = rxrpc_skb(jskb);
jsp->offset = offset;
jsp->len = RXRPC_JUMBO_DATALEN;
- rxrpc_input_data_one(call, jskb);
+ rxrpc_input_data_one(call, jskb, ¬ify);
+ rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);
sp->hdr.flags = jhdr.flags;
sp->hdr._rsvd = ntohs(jhdr._rsvd);
@@ -529,7 +532,11 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb
sp->offset = offset;
sp->len = len;
- rxrpc_input_data_one(call, skb);
+ rxrpc_input_data_one(call, skb, ¬ify);
+ if (notify) {
+ trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);
+ rxrpc_notify_socket(call);
+ }
return true;
protocol_error:
@@ -552,10 +559,8 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
skb->len, seq0);
state = READ_ONCE(call->state);
- if (state >= RXRPC_CALL_COMPLETE) {
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
+ if (state >= RXRPC_CALL_COMPLETE)
return;
- }
/* Unshare the packet so that it can be modified for in-place
* decryption.
@@ -605,7 +610,6 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
out:
trace_rxrpc_notify_socket(call->debug_id, serial);
rxrpc_notify_socket(call);
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
_leave(" [queued]");
}
@@ -797,7 +801,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
struct rxrpc_ackpacket ack;
struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
struct rxrpc_ackinfo info;
- struct sk_buff *skb_old = NULL, *skb_put = skb;
+ struct sk_buff *skb_old = NULL;
rxrpc_serial_t ack_serial, acked_serial;
rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
int nr_acks, offset, ioffset;
@@ -963,6 +967,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
goto out;
}
+ rxrpc_get_skb(skb, rxrpc_skb_get_ack);
spin_lock(&call->acks_ack_lock);
skb_old = call->acks_soft_tbl;
call->acks_soft_tbl = skb;
@@ -970,7 +975,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
rxrpc_input_soft_acks(call, skb->data + offset, first_soft_ack,
nr_acks, &summary);
- skb_put = NULL;
} else if (call->acks_soft_tbl) {
spin_lock(&call->acks_ack_lock);
skb_old = call->acks_soft_tbl;
@@ -986,7 +990,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
rxrpc_congestion_management(call, skb, &summary, acked_serial);
out:
- rxrpc_free_skb(skb_put, rxrpc_skb_put_input);
rxrpc_free_skb(skb_old, rxrpc_skb_put_ack);
}
@@ -1037,11 +1040,11 @@ void rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
switch (sp->hdr.type) {
case RXRPC_PACKET_TYPE_DATA:
rxrpc_input_data(call, skb);
- goto no_free;
+ break;
case RXRPC_PACKET_TYPE_ACK:
rxrpc_input_ack(call, skb);
- goto no_free;
+ break;
case RXRPC_PACKET_TYPE_BUSY:
/* Just ignore BUSY packets from the server; the retry and
@@ -1061,10 +1064,6 @@ void rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
default:
break;
}
-
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
-no_free:
- _leave("");
}
/*
diff --git a/net/rxrpc/io_thread.c b/net/rxrpc/io_thread.c
index 2119941b6d6c..91b8ba5b90db 100644
--- a/net/rxrpc/io_thread.c
+++ b/net/rxrpc/io_thread.c
@@ -72,6 +72,7 @@ static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
{
_enter("%p,%p", conn, skb);
+ rxrpc_get_skb(skb, rxrpc_skb_get_conn_work);
skb_queue_tail(&conn->rx_queue, skb);
rxrpc_queue_conn(conn, rxrpc_conn_queue_rx_work);
}
@@ -86,10 +87,9 @@ static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
_enter("%p,%p", local, skb);
if (rxrpc_get_local_maybe(local, rxrpc_local_get_queue)) {
+ rxrpc_get_skb(skb, rxrpc_skb_get_local_work);
skb_queue_tail(&local->event_queue, skb);
rxrpc_queue_local(local);
- } else {
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
}
}
@@ -99,10 +99,9 @@ static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
{
if (rxrpc_get_local_maybe(local, rxrpc_local_get_queue)) {
+ rxrpc_get_skb(skb, rxrpc_skb_get_reject_work);
skb_queue_tail(&local->reject_queue, skb);
rxrpc_queue_local(local);
- } else {
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
}
}
@@ -153,7 +152,7 @@ static bool rxrpc_extract_abort(struct sk_buff *skb)
/*
* Process packets received on the local endpoint
*/
-static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
+static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff **_skb)
{
struct rxrpc_connection *conn;
struct rxrpc_channel *chan;
@@ -161,6 +160,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
struct rxrpc_skb_priv *sp;
struct rxrpc_peer *peer = NULL;
struct rxrpc_sock *rx = NULL;
+ struct sk_buff *skb = *_skb;
unsigned int channel;
if (skb->tstamp == 0)
@@ -181,7 +181,6 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
static int lose;
if ((lose++ & 7) == 7) {
trace_rxrpc_rx_lose(sp);
- rxrpc_free_skb(skb, rxrpc_skb_put_lose);
return 0;
}
}
@@ -193,13 +192,13 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
switch (sp->hdr.type) {
case RXRPC_PACKET_TYPE_VERSION:
if (rxrpc_to_client(sp))
- goto discard;
+ return 0;
rxrpc_post_packet_to_local(local, skb);
- goto out;
+ return 0;
case RXRPC_PACKET_TYPE_BUSY:
if (rxrpc_to_server(sp))
- goto discard;
+ return 0;
fallthrough;
case RXRPC_PACKET_TYPE_ACK:
case RXRPC_PACKET_TYPE_ACKALL:
@@ -208,7 +207,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
break;
case RXRPC_PACKET_TYPE_ABORT:
if (!rxrpc_extract_abort(skb))
- return true; /* Just discard if malformed */
+ return 0; /* Just discard if malformed */
break;
case RXRPC_PACKET_TYPE_DATA:
@@ -220,15 +219,16 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
* decryption.
*/
if (sp->hdr.securityIndex != 0) {
- struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
- if (!nskb) {
- rxrpc_eaten_skb(skb, rxrpc_skb_eaten_by_unshare_nomem);
- goto out;
+ skb = skb_unshare(skb, GFP_ATOMIC);
+ if (!skb) {
+ rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare_nomem);
+ *_skb = NULL;
+ return 0;
}
- if (nskb != skb) {
- rxrpc_eaten_skb(skb, rxrpc_skb_eaten_by_unshare);
- skb = nskb;
+ if (skb != *_skb) {
+ rxrpc_eaten_skb(*_skb, rxrpc_skb_eaten_by_unshare);
+ *_skb = skb;
rxrpc_new_skb(skb, rxrpc_skb_new_unshared);
sp = rxrpc_skb(skb);
}
@@ -237,18 +237,18 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
case RXRPC_PACKET_TYPE_CHALLENGE:
if (rxrpc_to_server(sp))
- goto discard;
+ return 0;
break;
case RXRPC_PACKET_TYPE_RESPONSE:
if (rxrpc_to_client(sp))
- goto discard;
+ return 0;
break;
/* Packet types 9-11 should just be ignored. */
case RXRPC_PACKET_TYPE_PARAMS:
case RXRPC_PACKET_TYPE_10:
case RXRPC_PACKET_TYPE_11:
- goto discard;
+ return 0;
default:
goto bad_message;
@@ -268,7 +268,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
sp->hdr.seq == 1)
goto unsupported_service;
- goto discard;
+ return 0;
}
}
@@ -294,7 +294,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
/* Connection-level packet */
_debug("CONN %p {%d}", conn, conn->debug_id);
rxrpc_post_packet_to_conn(conn, skb);
- goto out;
+ return 0;
}
if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
@@ -306,19 +306,19 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
/* Ignore really old calls */
if (sp->hdr.callNumber < chan->last_call)
- goto discard;
+ return 0;
if (sp->hdr.callNumber == chan->last_call) {
if (chan->call ||
sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
- goto discard;
+ return 0;
/* For the previous service call, if completed
* successfully, we discard all further packets.
*/
if (rxrpc_conn_is_service(conn) &&
chan->last_type == RXRPC_PACKET_TYPE_ACK)
- goto discard;
+ return 0;
/* But otherwise we need to retransmit the final packet
* from data cached in the connection record.
@@ -329,7 +329,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
sp->hdr.serial,
sp->hdr.flags);
rxrpc_post_packet_to_conn(conn, skb);
- goto out;
+ return 0;
}
call = rcu_dereference(chan->call);
@@ -357,21 +357,14 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
goto bad_message;
if (sp->hdr.seq != 1)
- goto discard;
+ return 0;
call = rxrpc_new_incoming_call(local, rx, skb);
if (!call)
goto reject_packet;
}
- /* Process a call packet; this either discards or passes on the ref
- * elsewhere.
- */
+ /* Process a call packet. */
rxrpc_input_call_event(call, skb);
- goto out;
-
-discard:
- rxrpc_free_skb(skb, rxrpc_skb_put_input);
-out:
trace_rxrpc_rx_done(0, 0);
return 0;
@@ -400,9 +393,7 @@ static int rxrpc_input_packet(struct rxrpc_local *local, struct sk_buff *skb)
post_abort:
skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
reject_packet:
- trace_rxrpc_rx_done(skb->mark, skb->priority);
rxrpc_reject_packet(local, skb);
- _leave(" [badmsg]");
return 0;
}
@@ -441,9 +432,12 @@ int rxrpc_io_thread(void *data)
if ((skb = __skb_dequeue(&rx_queue))) {
switch (skb->mark) {
case RXRPC_SKB_MARK_PACKET:
+ skb->priority = 0;
rcu_read_lock();
- rxrpc_input_packet(local, skb);
+ rxrpc_input_packet(local, &skb);
rcu_read_unlock();
+ trace_rxrpc_rx_done(skb->mark, skb->priority);
+ rxrpc_free_skb(skb, rxrpc_skb_put_input);
break;
case RXRPC_SKB_MARK_ERROR:
rxrpc_input_error(local, skb);