tracepoint: static call: Compare data on transition from 2->1 callees

commit f7ec4121256393e1d03274acdca73eb18958f27e upstream.

On transition from 2->1 callees, we should be comparing .data rather
than .func, because the same callback can be registered twice with
different data, and what we care about here is that the data of array
element 0 is unchanged to skip rcu sync.

Link: https://lkml.kernel.org/r/20210805132717.23813-2-mathieu.desnoyers@efficios.com
Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Stefan Metzmacher <metze@samba.org>
Fixes: 547305a64632 ("tracepoint: Fix out of sync data passing by static caller")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 1f49063..ceb851c 100644 (file)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -359,7 +359,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
        } else {
                rcu_assign_pointer(tp->funcs, tp_funcs);
                tracepoint_update_call(tp, tp_funcs,
-                                      tp_funcs[0].func != old[0].func);
+                                      tp_funcs[0].data != old[0].data);
        }
        release_probes(old);
        return 0;