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Subject[PATCH 09/15] rxrpc: Allow the kernel to mark a call as being non-interruptible
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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>
---

Documentation/networking/rxrpc.txt | 11 ++++++++++-
fs/afs/rxrpc.c | 1 +
include/net/af_rxrpc.h | 1 +
net/rxrpc/af_rxrpc.c | 3 +++
net/rxrpc/ar-internal.h | 2 ++
net/rxrpc/call_object.c | 2 ++
net/rxrpc/conn_client.c | 8 ++++++--
net/rxrpc/sendmsg.c | 4 +++-
8 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index cd7303d7fa25..2e059e832034 100644
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -796,7 +796,9 @@ The kernel interface functions are as follows:
s64 tx_total_len,
gfp_t gfp,
rxrpc_notify_rx_t notify_rx,
- bool upgrade);
+ bool upgrade,
+ bool intr,
+ unsigned int debug_id);

This allocates the infrastructure to make a new RxRPC call and assigns
call and connection numbers. The call will be made on the UDP port that
@@ -824,6 +826,13 @@ The kernel interface functions are as follows:
the server upgrade the service to a better one. The resultant service ID
is returned by rxrpc_kernel_recv_data().

+ intr should be set to true if the call should be interruptible. If this
+ is not set, this function may not return until a channel has been
+ allocated; if it is set, the function may return -ERESTARTSYS.
+
+ debug_id is the call debugging ID to be used for tracing. This can be
+ obtained by atomically incrementing rxrpc_debug_id.
+
If this function is successful, an opaque reference to the RxRPC call is
returned. The caller now holds a reference on this and it must be
properly ended.
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index a34a89c75c6a..47cb5e6ef9bd 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -417,6 +417,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
afs_wake_up_async_call :
afs_wake_up_call_waiter),
call->upgrade,
+ true,
call->debug_id);
if (IS_ERR(rxcall)) {
ret = PTR_ERR(rxcall);
diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index 78c856cba4f5..e4d322c7dee6 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -45,6 +45,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *,
gfp_t,
rxrpc_notify_rx_t,
bool,
+ bool,
unsigned int);
int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
struct msghdr *, size_t,
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index ae8c5d7f3bf1..22760f4b5d17 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,
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