[PATCH net-next 26/35] rxrpc: Remove RCU from peer->error_targets list

From: David Howells
Date: Wed Nov 30 2022 - 12:02:51 EST


Remove the RCU requirements from the peer's list of error targets so that
the error distributor can call sleeping functions.

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

net/rxrpc/call_accept.c | 6 ++++++
net/rxrpc/call_object.c | 2 +-
net/rxrpc/conn_client.c | 4 ++++
net/rxrpc/conn_object.c | 6 +++---
net/rxrpc/output.c | 6 ------
net/rxrpc/peer_event.c | 15 ++++++++++++++-
6 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c
index 8bc327aa2beb..5f978b0b2404 100644
--- a/net/rxrpc/call_accept.c
+++ b/net/rxrpc/call_accept.c
@@ -433,6 +433,12 @@ struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
*/
rxrpc_put_call(call, rxrpc_call_put_discard_prealloc);

+ if (hlist_unhashed(&call->error_link)) {
+ spin_lock(&call->peer->lock);
+ hlist_add_head(&call->error_link, &call->peer->error_targets);
+ spin_unlock(&call->peer->lock);
+ }
+
_leave(" = %p{%d}", call, call->debug_id);
return call;

diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index 96a7edd3a842..7570b4e67bc5 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -442,7 +442,7 @@ void rxrpc_incoming_call(struct rxrpc_sock *rx,
rcu_assign_pointer(conn->channels[chan].call, call);

spin_lock(&conn->peer->lock);
- hlist_add_head_rcu(&call->error_link, &conn->peer->error_targets);
+ hlist_add_head(&call->error_link, &conn->peer->error_targets);
spin_unlock(&conn->peer->lock);

rxrpc_start_call_timer(call);
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index ab3dd22fadc0..3c7b1bdec0db 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -786,6 +786,10 @@ void rxrpc_expose_client_call(struct rxrpc_call *call)
if (chan->call_counter >= INT_MAX)
set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
trace_rxrpc_client(conn, channel, rxrpc_client_exposed);
+
+ spin_lock(&call->peer->lock);
+ hlist_add_head(&call->error_link, &call->peer->error_targets);
+ spin_unlock(&call->peer->lock);
}
}

diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
index c2e05ea29f12..5a39255ea014 100644
--- a/net/rxrpc/conn_object.c
+++ b/net/rxrpc/conn_object.c
@@ -215,9 +215,9 @@ void rxrpc_disconnect_call(struct rxrpc_call *call)
call->peer->cong_ssthresh = call->cong_ssthresh;

if (!hlist_unhashed(&call->error_link)) {
- spin_lock_bh(&call->peer->lock);
- hlist_del_rcu(&call->error_link);
- spin_unlock_bh(&call->peer->lock);
+ spin_lock(&call->peer->lock);
+ hlist_del_init(&call->error_link);
+ spin_unlock(&call->peer->lock);
}

if (rxrpc_is_client_call(call))
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index c8147e50060b..71963b4523be 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -394,12 +394,6 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)

_enter("%x,{%d}", txb->seq, txb->len);

- if (hlist_unhashed(&call->error_link)) {
- spin_lock_bh(&call->peer->lock);
- hlist_add_head_rcu(&call->error_link, &call->peer->error_targets);
- spin_unlock_bh(&call->peer->lock);
- }
-
/* Each transmission of a Tx packet needs a new serial number */
serial = atomic_inc_return(&conn->serial);
txb->wire.serial = htonl(serial);
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index 94f63fb1bd67..97d017ca3dc4 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -207,11 +207,24 @@ static void rxrpc_distribute_error(struct rxrpc_peer *peer, int error,
enum rxrpc_call_completion compl)
{
struct rxrpc_call *call;
+ HLIST_HEAD(error_targets);
+
+ spin_lock(&peer->lock);
+ hlist_move_list(&peer->error_targets, &error_targets);
+
+ while (!hlist_empty(&error_targets)) {
+ call = hlist_entry(error_targets.first,
+ struct rxrpc_call, error_link);
+ hlist_del_init(&call->error_link);
+ spin_unlock(&peer->lock);

- hlist_for_each_entry_rcu(call, &peer->error_targets, error_link) {
rxrpc_see_call(call, rxrpc_call_see_distribute_error);
rxrpc_set_call_completion(call, compl, 0, -error);
+
+ spin_lock(&peer->lock);
}
+
+ spin_unlock(&peer->lock);
}

/*