From: Sven Schnelle <svens@linux.ibm.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
netdev <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"linux-perf-use." <linux-perf-users@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel test robot <oliver.sang@intel.com>,
kbuild test robot <lkp@intel.com>,
Andrii Nakryiko <andrii@kernel.org>,
David Hildenbrand <david@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Michal Miroslaw <mirq-linux@rere.qmqm.pl>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Matthew Wilcox <willy@infradead.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Kees Cook <keescook@chromium.org>, Petr Mladek <pmladek@suse.com>
Subject: Re: [PATCH v2 7/7] tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN
Date: Mon, 29 Nov 2021 15:21:23 +0100 [thread overview]
Message-ID: <yt9d35nfvy8s.fsf@linux.ibm.com> (raw)
In-Reply-To: <CALOAHbDtqpkN4D0vHvGxTSpQkksMWtFm3faMy0n+pazxN_RPPg@mail.gmail.com> (Yafang Shao's message of "Mon, 29 Nov 2021 21:41:11 +0800")
Hi,
Yafang Shao <laoar.shao@gmail.com> writes:
> On Mon, Nov 29, 2021 at 6:13 PM Sven Schnelle <svens@linux.ibm.com> wrote:
>> > diff --git a/include/linux/sched.h b/include/linux/sched.h
>> > index 78c351e35fec..cecd4806edc6 100644
>> > --- a/include/linux/sched.h
>> > +++ b/include/linux/sched.h
>> > @@ -274,8 +274,13 @@ struct task_group;
>> >
>> > #define get_current_state() READ_ONCE(current->__state)
>> >
>> > -/* Task command name length: */
>> > -#define TASK_COMM_LEN 16
>> > +/*
>> > + * Define the task command name length as enum, then it can be visible to
>> > + * BPF programs.
>> > + */
>> > +enum {
>> > + TASK_COMM_LEN = 16,
>> > +};
>>
>> This breaks the trigger-field-variable-support.tc from the ftrace test
>> suite at least on s390:
>>
>> echo
>> 'hist:keys=next_comm:wakeup_lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).wakeup_latency($wakeup_lat,next_pid,sched.sched_waking.prio,next_comm)
>> if next_comm=="ping"'
>> linux/tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-field-variable-support.tc: line 15: echo: write error: Invalid argument
>>
>> I added a debugging line into check_synth_field():
>>
>> [ 44.091037] field->size 16, hist_field->size 16, field->is_signed 1, hist_field->is_signed 0
>>
>> Note the difference in the signed field.
>>
>
> Hi Sven,
>
> Thanks for the report and debugging!
> Seems we should explicitly define it as signed ?
> Could you pls. help verify it?
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index cecd4806edc6..44d36c6af3e1 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -278,7 +278,7 @@ struct task_group;
> * Define the task command name length as enum, then it can be visible to
> * BPF programs.
> */
> -enum {
> +enum SignedEnum {
> TASK_COMM_LEN = 16,
> };
Umm no. What you're doing here is to define the name of the enum as
'SignedEnum'. This doesn't change the type. I think before C++0x you
couldn't force an enum type.
Regards
Sven
next prev parent reply other threads:[~2021-11-29 14:24 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 11:27 [PATCH v2 0/7] task comm cleanups Yafang Shao
2021-11-20 11:27 ` [PATCH v2 1/7] fs/exec: replace strlcpy with strscpy_pad in __set_task_comm Yafang Shao
2021-11-20 11:27 ` [PATCH v2 2/7] fs/exec: replace strncpy with strscpy_pad in __get_task_comm Yafang Shao
2021-11-20 11:27 ` [PATCH v2 3/7] drivers/infiniband: replace open-coded string copy with get_task_comm Yafang Shao
2021-11-20 11:27 ` [PATCH v2 4/7] fs/binfmt_elf: " Yafang Shao
2021-11-29 16:01 ` Steven Rostedt
2021-11-30 3:01 ` Yafang Shao
2021-11-30 14:22 ` Steven Rostedt
2021-11-30 15:53 ` Yafang Shao
2021-11-20 11:27 ` [PATCH v2 5/7] samples/bpf/test_overhead_kprobe_kern: replace bpf_probe_read_kernel with bpf_probe_read_kernel_str to get task comm Yafang Shao
2021-11-20 11:27 ` [PATCH v2 6/7] tools/bpf/bpftool/skeleton: " Yafang Shao
2021-11-20 11:27 ` [PATCH v2 7/7] tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN Yafang Shao
2021-11-29 10:13 ` Sven Schnelle
2021-11-29 13:41 ` Yafang Shao
2021-11-29 14:21 ` Sven Schnelle [this message]
2021-11-29 14:32 ` David Hildenbrand
2021-11-29 14:38 ` Sven Schnelle
2021-11-29 15:33 ` Yafang Shao
2021-11-29 16:07 ` Steven Rostedt
2021-11-29 16:08 ` Steven Rostedt
2021-11-29 15:28 ` Yafang Shao
2021-11-29 17:30 ` Steven Rostedt
2021-11-29 17:56 ` Sven Schnelle
2021-11-30 3:03 ` Yafang Shao
2021-11-30 14:23 ` Steven Rostedt
2021-11-30 15:46 ` Yafang Shao
2023-02-08 21:55 ` John Stultz
2023-02-09 0:10 ` Alexei Starovoitov
2023-02-09 0:54 ` John Stultz
2023-02-09 2:06 ` Mathieu Desnoyers
2023-02-09 6:20 ` Yafang Shao
2023-02-09 14:27 ` Kajetan Puchalski
2023-02-09 15:37 ` Yafang Shao
2023-02-10 18:09 ` Kajetan Puchalski
2023-02-11 16:51 ` Qais Yousef
2023-02-12 3:19 ` Yafang Shao
2023-02-09 2:28 ` Steven Rostedt
2023-02-09 2:33 ` Steven Rostedt
2023-02-11 19:00 ` Steven Rostedt
2023-02-12 3:38 ` Yafang Shao
2023-02-12 3:44 ` Steven Rostedt
2023-02-13 17:43 ` Namhyung Kim
2023-02-13 17:46 ` Mathieu Desnoyers
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=yt9d35nfvy8s.fsf@linux.ibm.com \
--to=svens@linux.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=andrii.nakryiko@gmail.com \
--cc=andrii@kernel.org \
--cc=arnaldo.melo@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=david@redhat.com \
--cc=keescook@chromium.org \
--cc=laoar.shao@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=lkp@intel.com \
--cc=mathieu.desnoyers@efficios.com \
--cc=mirq-linux@rere.qmqm.pl \
--cc=netdev@vger.kernel.org \
--cc=oliver.sang@intel.com \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=rostedt@goodmis.org \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).