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

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>

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index fc32821f8240b78b61c12c4bc352bcfea041e2a9..133b6454b287ad4dde2268d7a53beaee814a1f45 100644 (file)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -338,7 +338,7 @@ 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;