rxrpc: Allow the kernel to mark a call as being non-interruptible

Allow kernel services using AF_RXRPC to indicate that a call should be
non-interruptible.  This allows kafs to make things like lock-extension and
writeback data storage calls non-interruptible.

If this is set, signals will be ignored for operations on that call where
possible - such as waiting to get a call channel on an rxrpc connection.

It doesn't prevent UDP sendmsg from being interrupted, but that will be
handled by packet retransmission.

rxrpc_kernel_recv_data() isn't affected by this since that never waits,
preferring instead to return -EAGAIN and leave the waiting to the caller.

Userspace initiated calls can't be set to be uninterruptible at this time.

Signed-off-by: David Howells <dhowells@redhat.com>

5 files changed, 16 insertions, 3 deletions

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 213935fbbbf7..ffde5b187f5d 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -270,6 +270,7 @@ static int rxrpc_listen(struct socket *sock, int backlog)
  * @gfp: The allocation constraints
  * @notify_rx: Where to send notifications instead of socket queue
  * @upgrade: Request service upgrade for call
+ * @intr: The call is interruptible
  * @debug_id: The debug ID for tracing to be assigned to the call
  *
  * Allow a kernel service to begin a call on the nominated socket.  This just
@@ -287,6 +288,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 					   gfp_t gfp,
 					   rxrpc_notify_rx_t notify_rx,
 					   bool upgrade,
+					   bool intr,
 					   unsigned int debug_id)
 {
 	struct rxrpc_conn_parameters cp;
@@ -311,6 +313,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 	memset(&p, 0, sizeof(p));
 	p.user_call_ID = user_call_ID;
 	p.tx_total_len = tx_total_len;
+	p.intr = intr;
 
 	memset(&cp, 0, sizeof(cp));
 	cp.local		= rx->local;
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 062ca9dc29b8..07fc1dfa4878 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -482,6 +482,7 @@ enum rxrpc_call_flag {
 	RXRPC_CALL_BEGAN_RX_TIMER,	/* We began the expect_rx_by timer */
 	RXRPC_CALL_RX_HEARD,		/* The peer responded at least once to this call */
 	RXRPC_CALL_RX_UNDERRUN,		/* Got data underrun */
+	RXRPC_CALL_IS_INTR,		/* The call is interruptible */
 };
 
 /*
@@ -711,6 +712,7 @@ struct rxrpc_call_params {
 		u32		normal;		/* Max time since last call packet (msec) */
 	} timeouts;
 	u8			nr_timeouts;	/* Number of timeouts specified */
+	bool			intr;		/* The call is interruptible */
 };
 
 struct rxrpc_send_params {
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index fe96881a334d..d0ca98d7aef5 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -241,6 +241,8 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
 		return call;
 	}
 
+	if (p->intr)
+		__set_bit(RXRPC_CALL_IS_INTR, &call->flags);
 	call->tx_total_len = p->tx_total_len;
 	trace_rxrpc_call(call, rxrpc_call_new_client, atomic_read(&call->usage),
 			 here, (const void *)p->user_call_ID);
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 83797b3949e2..5cf5595a14d8 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -656,10 +656,14 @@ static int rxrpc_wait_for_channel(struct rxrpc_call *call, gfp_t gfp)
 
 		add_wait_queue_exclusive(&call->waitq, &myself);
 		for (;;) {
-			set_current_state(TASK_INTERRUPTIBLE);
+			if (test_bit(RXRPC_CALL_IS_INTR, &call->flags))
+				set_current_state(TASK_INTERRUPTIBLE);
+			else
+				set_current_state(TASK_UNINTERRUPTIBLE);
 			if (call->call_id)
 				break;
-			if (signal_pending(current)) {
+			if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
+			    signal_pending(current)) {
 				ret = -ERESTARTSYS;
 				break;
 			}
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index bec64deb7b0a..45a05d9a27fa 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -80,7 +80,8 @@ static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
 		if (call->state >= RXRPC_CALL_COMPLETE)
 			return call->error;
 
-		if (timeout == 0 &&
+		if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
+		    timeout == 0 &&
 		    tx_win == tx_start && signal_pending(current))
 			return -EINTR;
 
@@ -620,6 +621,7 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
 		.call.tx_total_len	= -1,
 		.call.user_call_ID	= 0,
 		.call.nr_timeouts	= 0,
+		.call.intr		= true,
 		.abort_code		= 0,
 		.command		= RXRPC_CMD_SEND_DATA,
 		.exclusive		= false,