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Message-ID: <04e74fd214a01bee0fb5ac690730cb386536cced.camel@perches.com>
Date: Mon, 17 Jul 2023 15:34:14 -0700
From: Joe Perches <joe@...ches.com>
To: "Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...a.com,
rostedt@...dmis.org, Andy Whitcroft <apw@...onical.com>,
Dwaipayan Ray <dwaipayanray1@...il.com>,
Lukas Bulwahn <lukas.bulwahn@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
John Fastabend <john.fastabend@...il.com>, bpf@...r.kernel.org
Subject: Re: [PATCH rcu 5/5] checkpatch: Complain about unexpected uses of
RCU Tasks Trace
On Mon, 2023-07-17 at 11:04 -0700, Paul E. McKenney wrote:
> 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.
>
> Cc: Andy Whitcroft <apw@...onical.com> (maintainer:CHECKPATCH)
> Cc: Joe Perches <joe@...ches.com> (maintainer:CHECKPATCH)
> Cc: Dwaipayan Ray <dwaipayanray1@...il.com> (reviewer:CHECKPATCH)
> Cc: Lukas Bulwahn <lukas.bulwahn@...il.com>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: John Fastabend <john.fastabend@...il.com>
> Cc: <bpf@...r.kernel.org>
> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> ---
> scripts/checkpatch.pl | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -7457,6 +7457,24 @@ sub process {
> }
> }
>
> +# Complain about RCU Tasks Trace used outside of BPF (and of course, RCU).
> + if ($line =~ /\brcu_read_lock_trace\s*\(/ ||
> + $line =~ /\brcu_read_lock_trace_held\s*\(/ ||
> + $line =~ /\brcu_read_unlock_trace\s*\(/ ||
> + $line =~ /\bcall_rcu_tasks_trace\s*\(/ ||
> + $line =~ /\bsynchronize_rcu_tasks_trace\s*\(/ ||
> + $line =~ /\brcu_barrier_tasks_trace\s*\(/ ||
> + $line =~ /\brcu_request_urgent_qs_task\s*\(/) {
> + if ($realfile !~ m@...rnel/bpf@ &&
> + $realfile !~ m@...clude/linux/bpf@ &&
> + $realfile !~ m@...t/bpf@ &&
> + $realfile !~ m@...rnel/rcu@ &&
> + $realfile !~ m@...clude/linux/rcu@) {
Functions and paths like these tend to be accreted.
Please use a variable or 2 like:
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 $rcu_trace_paths = qr{(?x:
kernel/bfp/ |
include/linux/bpf |
net/bpf/ |
kernel/rcu/ |
include/linux/rcu
)};
...
if ($line =~ /\b($rcu_trace_funcs)\s*\(/ &&
$realfile !~ m{^$rcu_trace_paths}) {
WARN("RCU_TASKS_TRACE",
"use of RCU tasks trace '$1' is incorrect outside BPF or core RCU code\n" . $herecurr); }
}
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