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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	stable@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Stefan Metzmacher <metze@samba.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [for-linus][PATCH 1/3] tracepoint: static call: Compare data on transition from 2->1 callees
Date: Fri, 06 Aug 2021 10:53:00 -0400	[thread overview]
Message-ID: <20210806145407.819812399@goodmis.org> (raw)
In-Reply-To: <20210806145259.240934834@goodmis.org>

From: Mathieu Desnoyers <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.

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>
---
 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;
-- 
2.30.2

  reply	other threads:[~2021-08-06 14:54 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-06 14:52 [for-linus][PATCH 0/3] tracing: Fix tracepoint and static call race condition` Steven Rostedt
2021-08-06 14:53 ` Steven Rostedt [this message]
2021-08-06 14:53 ` [for-linus][PATCH 2/3] tracepoint: Fix static call function vs data state mismatch Steven Rostedt
2021-08-06 14:53 ` [for-linus][PATCH 3/3] tracepoint: Use rcu get state and cond sync for static call updates Steven Rostedt

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