[PATCH 6.18 65/83] rxrpc: Fix call removal to use RCU safe deletion

Greg Kroah-Hartman
2026-04-13T16:09:38Z

From: David Howells <dhowells@redhat.com>

commit 146d4ab94cf129ee06cd467cb5c71368a6b5bad6 upstream.

Fix rxrpc call removal from the rxnet->calls list to use list_del_rcu()
rather than list_del_init() to prevent stuffing up reading
/proc/net/rxrpc/calls from potentially getting into an infinite loop.

This, however, means that list_empty() no longer works on an entry that's
been deleted from the list, making it harder to detect prior deletion. Fix
this by:

Firstly, make rxrpc_destroy_all_calls() only dump the first ten calls that
are unexpectedly still on the list. Limiting the number of steps means
there's no need to call cond_resched() or to remove calls from the list
here, thereby eliminating the need for rxrpc_put_call() to check for that.

rxrpc_put_call() can then be fixed to unconditionally delete the call from
the list as it is the only place that the deletion occurs.

Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing")
Closes: https://sashiko.dev/#/patchset/20260319150150.4189381-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Linus Torvalds <torvalds@linux-foundation.org>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260408121252.2249051-5-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/trace/events/rxrpc.h | 2 +-
net/rxrpc/call_object.c | 24 +++++++++---------------
2 files changed, 10 insertions(+), 16 deletions(-)

--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -347,7 +347,7 @@
EM(rxrpc_call_see_release, "SEE release ") \
EM(rxrpc_call_see_userid_exists, "SEE u-exists") \
EM(rxrpc_call_see_waiting_call, "SEE q-conn ") \
- E_(rxrpc_call_see_zap, "SEE zap ")
+ E_(rxrpc_call_see_still_live, "SEE !still-l")

#define rxrpc_txqueue_traces \
EM(rxrpc_txqueue_await_reply, "AWR") \
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -654,11 +654,9 @@ void rxrpc_put_call(struct rxrpc_call *c
if (dead) {
ASSERTCMP(__rxrpc_call_state(call), ==, RXRPC_CALL_COMPLETE);

- if (!list_empty(&call->link)) {
- spin_lock(&rxnet->call_lock);
- list_del_init(&call->link);
- spin_unlock(&rxnet->call_lock);
- }
+ spin_lock(&rxnet->call_lock);
+ list_del_rcu(&call->link);
+ spin_unlock(&rxnet->call_lock);

rxrpc_cleanup_call(call);
}
@@ -730,24 +728,20 @@ void rxrpc_destroy_all_calls(struct rxrp
_enter("");

if (!list_empty(&rxnet->calls)) {
- spin_lock(&rxnet->call_lock);
+ int shown = 0;

- while (!list_empty(&rxnet->calls)) {
- call = list_entry(rxnet->calls.next,
- struct rxrpc_call, link);
- _debug("Zapping call %p", call);
+ spin_lock(&rxnet->call_lock);

- rxrpc_see_call(call, rxrpc_call_see_zap);
- list_del_init(&call->link);
+ list_for_each_entry(call, &rxnet->calls, link) {
+ rxrpc_see_call(call, rxrpc_call_see_still_live);

pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n",
call, refcount_read(&call->ref),
rxrpc_call_states[__rxrpc_call_state(call)],
call->flags, call->events);

- spin_unlock(&rxnet->call_lock);
- cond_resched();
- spin_lock(&rxnet->call_lock);
+ if (++shown >= 10)
+ break;
}

spin_unlock(&rxnet->call_lock);