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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2019-10-11 17:39:57 -0400
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-10-12 20:44:07 -0400
commit8530dec63e7b486e3761cc3d74a22de301845ff5 (patch)
treebea5a6cbbfacf3b79428040486d3eb016d419289 /kernel/trace/trace_events_hist.c
parentaa07d71f1bc7ea20e442e812b5de9d632b7f84c6 (diff)
tracing: Add tracing_check_open_get_tr()
Currently, most files in the tracefs directory test if tracing_disabled is set. If so, it should return -ENODEV. The tracing_disabled is called when tracing is found to be broken. Originally it was done in case the ring buffer was found to be corrupted, and we wanted to prevent reading it from crashing the kernel. But it's also called if a tracing selftest fails on boot. It's a one way switch. That is, once it is triggered, tracing is disabled until reboot. As most tracefs files can also be used by instances in the tracefs directory, they need to be carefully done. Each instance has a trace_array associated to it, and when the instance is removed, the trace_array is freed. But if an instance is opened with a reference to the trace_array, then it requires looking up the trace_array to get its ref counter (as there could be a race with it being deleted and the open itself). Once it is found, a reference is added to prevent the instance from being removed (and the trace_array associated with it freed). Combine the two checks (tracing_disabled and trace_array_get()) into a single helper function. This will also make it easier to add lockdown to tracefs later. Link: http://lkml.kernel.org/r/20191011135458.7399da44@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_events_hist.c')
-rw-r--r--kernel/trace/trace_events_hist.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 9468bd8d44a2..dd18d76bf1bd 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1680,7 +1680,7 @@ static int save_hist_vars(struct hist_trigger_data *hist_data)
if (var_data)
return 0;
- if (trace_array_get(tr) < 0)
+ if (tracing_check_open_get_tr(tr))
return -ENODEV;
var_data = kzalloc(sizeof(*var_data), GFP_KERNEL);