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    SubjectRe: [PATCH rcu 5/5] checkpatch: Complain about unexpected uses of RCU Tasks Trace
    On Thu, Jul 20, 2023 at 09:38:51PM -0700, Joe Perches wrote:
    > On Thu, 2023-07-20 at 20:56 -0700, Paul E. McKenney wrote:
    >
    > >
    > > > That works much better, thank you! I will update the patch on my
    > > > next rebase.
    > >
    > > As shown below. Is this what you had in mind?
    > []
    > > commit 496aa3821b40459b107f4bbc14ca867daad21fb6
    > > Author: Paul E. McKenney <paulmck@kernel.org>
    > > Date: Thu Jul 6 11:48:07 2023 -0700
    > >
    > > checkpatch: Complain about unexpected uses of RCU Tasks Trace
    > >
    > > RCU Tasks Trace is quite specialized, having been created specifically
    > > for sleepable BPF programs. Because it allows general blocking within
    > > readers, any new use of RCU Tasks Trace must take current use cases into
    > > account. Therefore, update checkpatch.pl to complain about use of any of
    > > the RCU Tasks Trace API members outside of BPF and outside of RCU itself.
    > []
    > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
    > []
    > > @@ -7457,6 +7457,30 @@ sub process {
    > > }
    > > }
    > >
    > > +# Complain about RCU Tasks Trace used outside of BPF (and of course, RCU).
    > > + our $rcu_trace_funcs = qr{(?x:
    > > + rcu_read_lock_trace |
    > > + rcu_read_lock_trace_held |
    > > + rcu_read_unlock_trace |
    > > + call_rcu_tasks_trace |
    > > + synchronize_rcu_tasks_trace |
    > > + rcu_barrier_tasks_trace |
    > > + rcu_request_urgent_qs_task
    > > + )};
    > > + our $rcu_trace_paths = qr{(?x:
    > > + kernel/bpf/ |
    > > + include/linux/bpf |
    > > + net/bpf/ |
    > > + kernel/rcu/ |
    > > + include/linux/rcu
    > > + )};
    > > + if ($line =~ /\b$rcu_trace_funcs\s*\(/) {
    > > + if ($realfile !~ m@^$rcu_trace_paths@) {
    > > + WARN("RCU_TASKS_TRACE",
    > > + "use of RCU tasks trace is incorrect outside BPF or core RCU code\n" . $herecurr);
    >
    > Exactly yes.
    >
    > (though I still suggest a capture group to show the function like below)
    >
    > if ($line =~ /\b($rcu_trace_funcs)\s*\(/ &&
    > $realfile !~ m{^$rcu_trace_paths}) {
    > WARN("RCU_TASKS_TRACE",
    > "use of RCU task trace '$1' is incorrect outside BPF or core RCU code\n" . $herecurr);
    > }

    That does seem to work!

    I will fold this change in on my next rebase.

    Thanx, Paul

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