[PATCH net-next 05/17] rxrpc: Remove call->input_lock

From: David Howells
Date: Wed Nov 23 2022 - 05:32:41 EST


Remove call->input_lock as it was only necessary to serialise access to the
state stored in the rxrpc_call struct by simultaneous softirq handlers
presenting received packets. They now dump the packets in a queue and a
single process-context handler now processes them.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
---

net/rxrpc/ar-internal.h | 1 -
net/rxrpc/call_object.c | 1 -
net/rxrpc/input.c | 22 +++++-----------------
3 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 9ab835125ebf..641fc9e1dc27 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -653,7 +653,6 @@ struct rxrpc_call {
rxrpc_seq_t rx_consumed; /* Highest packet consumed */
rxrpc_serial_t rx_serial; /* Highest serial received for this call */
u8 rx_winsize; /* Size of Rx window */
- spinlock_t input_lock; /* Lock for packet input to this call */

/* TCP-style slow-start congestion control [RFC5681]. Since the SMSS
* is fixed, we keep these numbers in terms of segments (ie. DATA
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index b098e72563a7..01ffe99516b8 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -151,7 +151,6 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp,
init_waitqueue_head(&call->waitq);
spin_lock_init(&call->notify_lock);
spin_lock_init(&call->tx_lock);
- spin_lock_init(&call->input_lock);
spin_lock_init(&call->acks_ack_lock);
rwlock_init(&call->state_lock);
refcount_set(&call->ref, 1);
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index f4f6f3c62d03..13c52145a926 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -588,8 +588,6 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
}
}

- spin_lock(&call->input_lock);
-
/* Received data implicitly ACKs all of the request packets we sent
* when we're acting as a client.
*/
@@ -607,8 +605,6 @@ 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);
-
- spin_unlock(&call->input_lock);
rxrpc_free_skb(skb, rxrpc_skb_put_input);
_leave(" [queued]");
}
@@ -811,7 +807,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
offset = sizeof(struct rxrpc_wire_header);
if (skb_copy_bits(skb, offset, &ack, sizeof(ack)) < 0) {
rxrpc_proto_abort("XAK", call, 0);
- goto out_not_locked;
+ goto out;
}
offset += sizeof(ack);

@@ -863,7 +859,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
rxrpc_is_client_call(call)) {
rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
0, -ENETRESET);
- return;
+ goto out;
}

/* If we get an OUT_OF_SEQUENCE ACK from the server, that can also
@@ -877,7 +873,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
rxrpc_is_client_call(call)) {
rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
0, -ENETRESET);
- return;
+ goto out;
}

/* Discard any out-of-order or duplicate ACKs (outside lock). */
@@ -885,7 +881,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
first_soft_ack, call->acks_first_seq,
prev_pkt, call->acks_prev_seq);
- goto out_not_locked;
+ goto out;
}

info.rxMTU = 0;
@@ -893,14 +889,12 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
if (skb->len >= ioffset + sizeof(info) &&
skb_copy_bits(skb, ioffset, &info, sizeof(info)) < 0) {
rxrpc_proto_abort("XAI", call, 0);
- goto out_not_locked;
+ goto out;
}

if (nr_acks > 0)
skb_condense(skb);

- spin_lock(&call->input_lock);
-
/* Discard any out-of-order or duplicate ACKs (inside lock). */
if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
@@ -992,8 +986,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)

rxrpc_congestion_management(call, skb, &summary, acked_serial);
out:
- spin_unlock(&call->input_lock);
-out_not_locked:
rxrpc_free_skb(skb_put, rxrpc_skb_put_input);
rxrpc_free_skb(skb_old, rxrpc_skb_put_ack);
}
@@ -1005,12 +997,8 @@ static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
{
struct rxrpc_ack_summary summary = { 0 };

- spin_lock(&call->input_lock);
-
if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
rxrpc_end_tx_phase(call, false, "ETL");
-
- spin_unlock(&call->input_lock);
}

/*