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Message-ID: <167034236532.1105287.7206596176961982004.stgit@warthog.procyon.org.uk>
Date: Tue, 06 Dec 2022 15:59:25 +0000
From: David Howells <dhowells@...hat.com>
To: netdev@...r.kernel.org
Cc: Marc Dionne <marc.dionne@...istor.com>,
linux-afs@...ts.infradead.org, dhowells@...hat.com,
linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next 06/32] rxrpc: Convert call->state_lock to a spinlock
Convert call->state_lock to a spinlock and use a barrier on it when setting
the completion state. The only readers can then be made to read it
locklessly.
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Marc Dionne <marc.dionne@...istor.com>
cc: linux-afs@...ts.infradead.org
---
net/rxrpc/ar-internal.h | 2 +-
net/rxrpc/call_object.c | 2 +-
net/rxrpc/conn_client.c | 4 ++--
net/rxrpc/conn_event.c | 4 ++--
net/rxrpc/input.c | 6 +++---
net/rxrpc/recvmsg.c | 23 ++++++++++++-----------
net/rxrpc/sendmsg.c | 17 ++++++-----------
7 files changed, 27 insertions(+), 31 deletions(-)
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 423f2e1eddb3..755395d1f2ca 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -622,7 +622,7 @@ struct rxrpc_call {
unsigned long flags;
unsigned long events;
spinlock_t notify_lock; /* Kernel notification lock */
- rwlock_t state_lock; /* lock for state transition */
+ spinlock_t state_lock; /* lock for state transition */
u32 abort_code; /* Local/remote abort code */
int error; /* Local error incurred */
enum rxrpc_call_state state; /* current state of call */
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index 36cc868b8922..07abf12e99bb 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -162,7 +162,7 @@ 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);
- rwlock_init(&call->state_lock);
+ spin_lock_init(&call->state_lock);
refcount_set(&call->ref, 1);
call->debug_id = debug_id;
call->tx_total_len = -1;
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 87efa0373aed..ec8913de42c9 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -555,9 +555,9 @@ static void rxrpc_activate_one_channel(struct rxrpc_connection *conn,
trace_rxrpc_connect_call(call);
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
call->state = RXRPC_CALL_CLIENT_SEND_REQUEST;
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
/* Paired with the read barrier in rxrpc_connect_call(). This orders
* cid and epoch in the connection wrt to call_id without the need to
diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
index dfd29882126f..f05d58636307 100644
--- a/net/rxrpc/conn_event.c
+++ b/net/rxrpc/conn_event.c
@@ -265,12 +265,12 @@ static void rxrpc_call_is_secure(struct rxrpc_call *call)
{
_enter("%p", call);
if (call) {
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
if (call->state == RXRPC_CALL_SERVER_SECURING) {
call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
rxrpc_notify_socket(call);
}
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
}
}
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index dbd92f09c2ca..3b2e8e7d2e0f 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -257,7 +257,7 @@ static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
state = call->state;
switch (state) {
@@ -278,7 +278,7 @@ static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
goto bad_state;
}
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
trace_rxrpc_txqueue(call, rxrpc_txqueue_await_reply);
else
@@ -287,7 +287,7 @@ static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
return true;
bad_state:
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
kdebug("end_tx %s", rxrpc_call_states[call->state]);
rxrpc_proto_abort(abort_why, call, call->tx_top);
return false;
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 0cde2b477711..a9c9b2a8a27a 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -70,7 +70,8 @@ bool __rxrpc_set_call_completion(struct rxrpc_call *call,
call->abort_code = abort_code;
call->error = error;
call->completion = compl;
- call->state = RXRPC_CALL_COMPLETE;
+ /* Allow reader of completion state to operate locklessly */
+ smp_store_release(&call->state, RXRPC_CALL_COMPLETE);
trace_rxrpc_call_complete(call);
wake_up(&call->waitq);
rxrpc_notify_socket(call);
@@ -87,9 +88,9 @@ bool rxrpc_set_call_completion(struct rxrpc_call *call,
bool ret = false;
if (call->state < RXRPC_CALL_COMPLETE) {
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
}
return ret;
}
@@ -107,9 +108,9 @@ bool rxrpc_call_completed(struct rxrpc_call *call)
bool ret = false;
if (call->state < RXRPC_CALL_COMPLETE) {
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
ret = __rxrpc_call_completed(call);
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
}
return ret;
}
@@ -131,9 +132,9 @@ bool rxrpc_abort_call(const char *why, struct rxrpc_call *call,
{
bool ret;
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
ret = __rxrpc_abort_call(why, call, seq, abort_code, error);
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
return ret;
}
@@ -193,23 +194,23 @@ static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY)
rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
switch (call->state) {
case RXRPC_CALL_CLIENT_RECV_REPLY:
__rxrpc_call_completed(call);
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
break;
case RXRPC_CALL_SERVER_RECV_REQUEST:
call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
rxrpc_propose_delay_ACK(call, serial,
rxrpc_propose_ack_processing_op);
break;
default:
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
break;
}
}
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index cde1e65f16b4..816c1b083a69 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -195,7 +195,7 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
if (last || call->state == RXRPC_CALL_SERVER_ACK_REQUEST) {
_debug("________awaiting reply/ACK__________");
- write_lock(&call->state_lock);
+ spin_lock(&call->state_lock);
switch (call->state) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
@@ -218,7 +218,7 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
default:
break;
}
- write_unlock(&call->state_lock);
+ spin_unlock(&call->state_lock);
}
if (poke)
@@ -354,12 +354,9 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
success:
ret = copied;
- if (READ_ONCE(call->state) == RXRPC_CALL_COMPLETE) {
- read_lock(&call->state_lock);
- if (call->error < 0)
- ret = call->error;
- read_unlock(&call->state_lock);
- }
+ if (smp_load_acquire(&call->state) == RXRPC_CALL_COMPLETE &&
+ call->error < 0)
+ ret = call->error;
out:
call->tx_pending = txb;
_leave(" = %d", ret);
@@ -715,7 +712,7 @@ int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call,
_debug("CALL %d USR %lx ST %d on CONN %p",
call->debug_id, call->user_call_ID, call->state, call->conn);
- switch (READ_ONCE(call->state)) {
+ switch (smp_load_acquire(&call->state)) {
case RXRPC_CALL_CLIENT_SEND_REQUEST:
case RXRPC_CALL_SERVER_ACK_REQUEST:
case RXRPC_CALL_SERVER_SEND_REPLY:
@@ -723,9 +720,7 @@ int rxrpc_kernel_send_data(struct socket *sock, struct rxrpc_call *call,
notify_end_tx, &dropped_lock);
break;
case RXRPC_CALL_COMPLETE:
- read_lock(&call->state_lock);
ret = call->error;
- read_unlock(&call->state_lock);
break;
default:
/* Request phase complete for this client call */
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