----- On Aug 5, 2021, at 1:07 PM, rostedt rostedt@goodmis.org wrote:
On Thu, 5 Aug 2021 09:27:15 -0400 Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
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://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba....
FYI, You only need to show one Fixes.
Fixes: d25e37d89dd2 ("tracepoint: Optimize using static_call()")
The above is fixed by the one below. Which means all the stable kernels that have the above, will also have the below, and thus the above is just redundant.
Fixes: 547305a64632 ("tracepoint: Fix out of sync data passing by static caller")
The above is what the patch actually fixes.
Fixes: 352384d5c84e ("tracepoints: Update static_call before tp_funcs when adding a tracepoint")
How does this patch fix the above? Perhaps the above did not go enough to fix the issue, but it's unrelated.
OK
I'll remove the first and last Fixes tag.
OK
Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Steven Rostedt rostedt@goodmis.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 Cc: stable@vger.kernel.org # 5.10+
The "# 5.10+" is now obsolete, and not needed. The Fixes tag is used to determine where this gets backported to.
Other than that. This patch looks good.
Great, thanks!
Mathieu
-- Steve
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);