Messages in this thread | | | Date | Fri, 6 Mar 2020 15:45:56 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v4 16/27] tracing: Remove regular RCU context for _rcuidle tracepoints (again) |
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On Fri, 6 Mar 2020 15:22:46 -0500 (EST) Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> I agree with the overall approach. Just a bit of nitpicking on the API: > > I understand that the "prio" argument is a separate argument because it can take > many values. However, "rcu" is just a boolean, so I wonder if we should not rather > introduce a "int flags" with a bitmask enum, e.g.
I thought about this approach, but thought it was a bit overkill. As the kernel doesn't have an internal API, I figured we can switch this over to flags when we get another flag to add. Unless you can think of one in the near future.
> > int tracepoint_probe_register_prio_flags(struct tracepoint *tp, void *probe, > void *data, int prio, int flags) > > where flags would be populated through OR between labels of this enum: > > enum tracepoint_flags { > TRACEPOINT_FLAG_RCU = (1U << 0), > }; > > We can then be future-proof for additional flags without ending up calling e.g. > > tracepoint_probe_register_featurea_featureb_featurec(tp, probe, data, 0, 1, 0, 1)
No, as soon as there is another boolean to add, the rcu version would be switched to flags. I even thought about making the rcu and prio into one, and change prio to be a SHRT_MAX max, and have the other 16 bits be for flags.
-- Steve
> > which seems rather error-prone and less readable than a set of flags.
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