Re: [PATCH v17 11/13] selftests: tracing: Add wprobe trigger testcases

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Tue, 22 Sep 2026 04:41:53 +0000
sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [Low] kselftest: trace buffer not cleared before verifying offline wprobe triggers
> - [Low] kselftest: missing set_wprobe dependency check in requires lines
> --
> 
> commit 0d531760cdf15ae449a5bc0545ea39a43134b990
> Author: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> selftests: tracing: Add wprobe trigger testcases
> 
> This commit adds several test scripts for wprobe triggers in the ftrace
> selftests. The test scripts verify setting and clearing wprobe triggers,
> CPU hotplug behavior for wprobes, and syntax error logging.
> 
> Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.1785067572.git.wangjinchao600@gmail.com/
> 
> > diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc
> > --- /dev/null
> > +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-hotplug.tc
> > @@ -0,0 +1,150 @@
> > +#!/bin/sh
> > +# SPDX-License-Identifier: GPL-2.0
> > +# description: event trigger - test wprobe trigger across cpu hotplug
> > +# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README events/sched/sched_process_fork/trigger "[(structname[,field])]<argname>[->field[->field|.field...]]":README
> 
> [Severity: Low]
> Should we check for set_wprobe in the README in this requires line? If a kernel
> has CONFIG_WPROBE_EVENTS=y but CONFIG_WPROBE_TRIGGERS=n, it seems this test
> will execute and fail unexpectedly with "Failed to set set_wprobe trigger"
> instead of being gracefully skipped as UNRESOLVED.

Ah, good catch! OK, let me add that in the requires line.

> 
> [ ... ]
> 
> > +:;: "Take target CPU offline" ;:
> > +echo 0 > $cpu/online
> > +sleep 1
> > +
> > +# Wait for sample_timer_cb to fire and set_wprobe trigger to activate while CPU is offline
> > +sleep 2
> > +
> > +:;: "Check set_wprobe trigger activated the watchpoint" ;:
> > +if ! grep -q watch trace; then
> > +  fail "Failed to trigger watchpoint while CPU is offline"
> > +fi
> 
> [Severity: Low]
> Does this grep falsely match events generated while the CPU was still online?
> Because the target fprobe (sample_timer_cb) fires continuously, the trace
> buffer could log a watch event before the offlining process actually completes.
> Should we add a clear_trace call either before or right after taking the CPU
> offline?

OK, let me add it.

Thanks!

-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>