On Thu, Jul 20, 2023 at 12:29:42AM -0700, Joe Perches wrote:
> On Mon, 2023-07-17 at 16:34 -0700, Paul E. McKenney wrote:
> > On Mon, Jul 17, 2023 at 03:34:14PM -0700, Joe Perches wrote:
> > > 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@xxxxxxxxxxxxx> (maintainer:CHECKPATCH)
> > > > Cc: Joe Perches <joe@xxxxxxxxxxx> (maintainer:CHECKPATCH)
> > > > Cc: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx> (reviewer:CHECKPATCH)
> > > > Cc: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> > > > Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> > > > Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> > > > Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> > > > Cc: <bpf@xxxxxxxxxxxxxxx>
> > > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > > > ---
> > > > 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@^kernel/bpf@ &&
> > > > + $realfile !~ m@^include/linux/bpf@ &&
> > > > + $realfile !~ m@^net/bpf@ &&
> > > > + $realfile !~ m@^kernel/rcu@ &&
> > > > + $realfile !~ m@^include/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/ |
> ^^
> kernel/bfp/ |
>
> (umm, oops...)
> I think my original suggestion works better when I don't typo the path.
Color me blind! ;-)
That works much better, thank you! I will update the patch on my
next rebase.
Thanx, Paul
> > > include/linux/bpf |
> > > net/bpf/ |
> > > kernel/rcu/ |
> > > include/linux/rcu
> > > )};
> >
> > Like this?
> >
> > # 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 $rcu_trace_paths = qr{(?x:
> > kernel/bfp/ |
> > include/linux/bpf |
> > net/bpf/ |
> > kernel/rcu/ |
> > include/linux/rcu
> > )};
> > if ($line =~ /$rcu_trace_funcs/) {
> > if ($realfile !~ m@^$rcu_trace_paths@) {
> > WARN("RCU_TASKS_TRACE",
> > "use of RCU tasks trace is incorrect outside BPF or core RCU code\n" . $herecurr);
> > }
> > }
> >
> > No, that is definitely wrong. It has lost track of the list of pathnames,
> > thus complaining about uses of those functions in files where their use
> > is permitted.
> >
> > But this seems to work:
> >
> > # Complain about RCU Tasks Trace used outside of BPF (and of course, RCU).
> > our $rcu_trace_funcs = qr{(?x:
> > rcu_read_lock_trace |
> > rcu_read_lock_trace_held |
> > rcu_read_unlock_trace |
> > call_rcu_tasks_trace |
> > synchronize_rcu_tasks_trace |
> > rcu_barrier_tasks_trace |
> > rcu_request_urgent_qs_task
> > )};
> > if ($line =~ /\b$rcu_trace_funcs\s*\(/) {
> > if ($realfile !~ m@^kernel/bpf@ &&
> > $realfile !~ m@^include/linux/bpf@ &&
> > $realfile !~ m@^net/bpf@ &&
> > $realfile !~ m@^kernel/rcu@ &&
> > $realfile !~ m@^include/linux/rcu@) {
> > WARN("RCU_TASKS_TRACE",
> > "use of RCU tasks trace is incorrect outside BPF or core RCU code\n" . $herecurr);
> > }
> > }
> >
> > Maybe the "^" needs to be distributed into $rcu_trace_paths?
> >
> > # 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 $rcu_trace_paths = qr{(?x:
> > ^kernel/bfp/ |
> > ^include/linux/bpf |
> > ^net/bpf/ |
> > ^kernel/rcu/ |
> > ^include/linux/rcu
> > )};
> > if ($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);
> > }
> > }
> >
> > But no joy here, either. Which is no surprise, given that perl is
> > happy to distribute the "\b" and the "\s*\(" across the elements of
> > $rcu_trace_funcs. I tried a number of other variations, including
> > inverting the "if" condition "(!(... =~ ...))", inverting the "if"
> > condition via an empty "then" clause, replacing the "m@" with "/",
> > replacing the "|" in the "qr{}" with "&", and a few others.
> >
> > Again, listing the pathnames explicitly in the second "if" condition
> > works just fine.
> >
> > Help?
> >
> > Thanx, Paul
>
