----- On Aug 5, 2021, at 1:07 PM, rostedt rostedt@xxxxxxxxxxx wrote: > On Thu, 5 Aug 2021 09:27:15 -0400 > Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> 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@xxxxxxxxx/ > > 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@xxxxxxxxxxxx> >> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> >> Cc: Ingo Molnar <mingo@xxxxxxxxxx> >> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx> >> Cc: Stefan Metzmacher <metze@xxxxxxxxx> >> Cc: <stable@xxxxxxxxxxxxxxx> # 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); >> } >> release_probes(old); > > return 0; -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
