[PATCH 5.4 119/155] afs: Fix client call Rx-phase signal handling

Greg Kroah-Hartman
2020-03-31T09:17:00Z

From: David Howells <dhowells@redhat.com>

commit 7d7587db0d7fd1138f2afcffdc46a8e15630b944 upstream.

Fix the handling of signals in client rxrpc calls made by the afs
filesystem. Ignore signals completely, leaving call abandonment or
connection loss to be detected by timeouts inside AF_RXRPC.

Allowing a filesystem call to be interrupted after the entire request has
been transmitted and an abort sent means that the server may or may not
have done the action - and we don't know. It may even be worse than that
for older servers.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/afs/rxrpc.c | 34 ++--------------------------------
include/net/af_rxrpc.h | 4 +---
net/rxrpc/af_rxrpc.c | 33 +++------------------------------
net/rxrpc/ar-internal.h | 1 -
net/rxrpc/input.c | 1 -
5 files changed, 6 insertions(+), 67 deletions(-)

--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -603,11 +603,7 @@ call_complete:
long afs_wait_for_call_to_complete(struct afs_call *call,
struct afs_addr_cursor *ac)
{
- signed long rtt2, timeout;
long ret;
- bool stalled = false;
- u64 rtt;
- u32 life, last_life;
bool rxrpc_complete = false;

DECLARE_WAITQUEUE(myself, current);
@@ -618,14 +614,6 @@ long afs_wait_for_call_to_complete(struc
if (ret < 0)
goto out;

- rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
- rtt2 = nsecs_to_jiffies64(rtt) * 2;
- if (rtt2 < 2)
- rtt2 = 2;
-
- timeout = rtt2;
- rxrpc_kernel_check_life(call->net->socket, call->rxcall, &last_life);
-
add_wait_queue(&call->waitq, &myself);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
@@ -636,37 +624,19 @@ long afs_wait_for_call_to_complete(struc
call->need_attention = false;
__set_current_state(TASK_RUNNING);
afs_deliver_to_call(call);
- timeout = rtt2;
continue;
}

if (afs_check_call_state(call, AFS_CALL_COMPLETE))
break;

- if (!rxrpc_kernel_check_life(call->net->socket, call->rxcall, &life)) {
+ if (!rxrpc_kernel_check_life(call->net->socket, call->rxcall)) {
/* rxrpc terminated the call. */
rxrpc_complete = true;
break;
}

- if (call->intr && timeout == 0 &&
- life == last_life && signal_pending(current)) {
- if (stalled)
- break;
- __set_current_state(TASK_RUNNING);
- rxrpc_kernel_probe_life(call->net->socket, call->rxcall);
- timeout = rtt2;
- stalled = true;
- continue;
- }
-
- if (life != last_life) {
- timeout = rtt2;
- last_life = life;
- stalled = false;
- }
-
- timeout = schedule_timeout(timeout);
+ schedule();
}

remove_wait_queue(&call->waitq, &myself);
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -58,9 +58,7 @@ int rxrpc_kernel_charge_accept(struct so
rxrpc_user_attach_call_t, unsigned long, gfp_t,
unsigned int);
void rxrpc_kernel_set_tx_length(struct socket *, struct rxrpc_call *, s64);
-bool rxrpc_kernel_check_life(const struct socket *, const struct rxrpc_call *,
- u32 *);
-void rxrpc_kernel_probe_life(struct socket *, struct rxrpc_call *);
+bool rxrpc_kernel_check_life(const struct socket *, const struct rxrpc_call *);
u32 rxrpc_kernel_get_epoch(struct socket *, struct rxrpc_call *);
bool rxrpc_kernel_get_reply_time(struct socket *, struct rxrpc_call *,
ktime_t *);
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -371,45 +371,18 @@ EXPORT_SYMBOL(rxrpc_kernel_end_call);
* rxrpc_kernel_check_life - Check to see whether a call is still alive
* @sock: The socket the call is on
* @call: The call to check
- * @_life: Where to store the life value
*
- * Allow a kernel service to find out whether a call is still alive - ie. we're
- * getting ACKs from the server. Passes back in *_life a number representing
- * the life state which can be compared to that returned by a previous call and
- * return true if the call is still alive.
- *
- * If the life state stalls, rxrpc_kernel_probe_life() should be called and
- * then 2RTT waited.
+ * Allow a kernel service to find out whether a call is still alive -
+ * ie. whether it has completed.
*/
bool rxrpc_kernel_check_life(const struct socket *sock,
- const struct rxrpc_call *call,
- u32 *_life)
+ const struct rxrpc_call *call)
{
- *_life = call->acks_latest;
return call->state != RXRPC_CALL_COMPLETE;
}
EXPORT_SYMBOL(rxrpc_kernel_check_life);

/**
- * rxrpc_kernel_probe_life - Poke the peer to see if it's still alive
- * @sock: The socket the call is on
- * @call: The call to check
- *
- * In conjunction with rxrpc_kernel_check_life(), allow a kernel service to
- * find out whether a call is still alive by pinging it. This should cause the
- * life state to be bumped in about 2*RTT.
- *
- * The must be called in TASK_RUNNING state on pain of might_sleep() objecting.
- */
-void rxrpc_kernel_probe_life(struct socket *sock, struct rxrpc_call *call)
-{
- rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
- rxrpc_propose_ack_ping_for_check_life);
- rxrpc_send_ack_packet(call, true, NULL);
-}
-EXPORT_SYMBOL(rxrpc_kernel_probe_life);
-
-/**
* rxrpc_kernel_get_epoch - Retrieve the epoch value from a call.
* @sock: The socket the call is on
* @call: The call to query
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -675,7 +675,6 @@ struct rxrpc_call {

/* transmission-phase ACK management */
ktime_t acks_latest_ts; /* Timestamp of latest ACK received */
- rxrpc_serial_t acks_latest; /* serial number of latest ACK received */
rxrpc_seq_t acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
rxrpc_seq_t acks_lost_top; /* tx_top at the time lost-ack ping sent */
rxrpc_serial_t acks_lost_ping; /* Serial number of probe ACK */
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -882,7 +882,6 @@ static void rxrpc_input_ack(struct rxrpc
before(prev_pkt, call->ackr_prev_seq))
goto out;
call->acks_latest_ts = skb->tstamp;
- call->acks_latest = sp->hdr.serial;

call->ackr_first_seq = first_soft_ack;
call->ackr_prev_seq = prev_pkt;