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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Steven Rostedt <rostedt@goodmis.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Stefan Metzmacher <metze@samba.org>
Cc: linux-kernel@vger.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [RFC PATCH 1/3] Fix: tracepoint: static call: compare data on transition from 2->1 callees
Date: Tue, 27 Jul 2021 11:06:11 -0400	[thread overview]
Message-ID: <20210727150613.20886-2-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20210727150613.20886-1-mathieu.desnoyers@efficios.com>

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.

[ Build tested only. ]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 kernel/tracepoint.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index fc32821f8240..133b6454b287 100644
--- 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;
-- 
2.20.1


  reply	other threads:[~2021-07-27 15:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-27 15:06 [RFC PATCH 0/3] tracepoint static call fixes Mathieu Desnoyers
2021-07-27 15:06 ` Mathieu Desnoyers [this message]
2021-07-27 15:06 ` [RFC PATCH 2/3] Fix: tracepoint: static call function vs data state mismatch Mathieu Desnoyers
2021-07-27 15:06 ` [RFC PATCH 3/3] Fix: tracepoint: rcu get state and cond sync for static call updates Mathieu Desnoyers
2021-07-27 16:18   ` Paul E. McKenney
2021-07-27 19:13   ` [RFC PATCH v2] " Mathieu Desnoyers

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