From: Steven Rostedt <rostedt@goodmis.org>
To: patrick wang <patrick.wang.shcn@gmail.com>
Cc: paulmck@kernel.org, frederic@kernel.org,
quic_neeraju@quicinc.com, josh@joshtriplett.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
joel@joelfernandes.org, rcu@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu: ftrace: avoid tracing a few functions executed in multi_cpu_stop()
Date: Wed, 20 Apr 2022 11:44:54 -0400 [thread overview]
Message-ID: <20220420114454.69ab108c@gandalf.local.home> (raw)
In-Reply-To: <CAGcnep_Gx+3KiUvDVronYKn_divU3OM-RQEOPZakv7MRYh4EJw@mail.gmail.com>
On Wed, 20 Apr 2022 18:34:34 +0800
patrick wang <patrick.wang.shcn@gmail.com> wrote:
[ I had a power outage yesterday, just catching up now ]
> Sorry for the format. Need get used to gmail.
>
> These functions are running within stop machine and ftrace modify
> code by using stop machine to ensure the safety on some
> architectures(e.g. RISC-V). These functions' instructions will be
> modified during ftrace modifying code. When instructions are being
> modified, they shouldn't be executed typically. Or the executor
> may behave unpredictably.
Interesting. On x86 when we used stop machine[*] it was not an issue to
modify the code that is being executed in stop machine. I'm curious to
exactly what the issue is if something does get traced in the stop machine
processing. Why does it crash?
-- Steve
[*] You really should come up with a better way than stop machine, because
the stop machine method is really disruptive, can you not use the break
point method for updates?
next prev parent reply other threads:[~2022-04-20 15:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-18 4:37 [PATCH] rcu: ftrace: avoid tracing a few functions executed in multi_cpu_stop() Patrick Wang
2022-04-18 16:28 ` Paul E. McKenney
2022-04-18 18:34 ` Steven Rostedt
2022-04-19 4:06 ` patrick wang
2022-04-20 10:34 ` patrick wang
2022-04-20 15:44 ` Steven Rostedt [this message]
2022-04-20 16:26 ` Steven Rostedt
2022-04-21 11:36 ` patrick wang
2022-04-21 12:50 ` Steven Rostedt
2022-04-22 10:45 ` patrick wang
2022-04-22 15:52 ` Steven Rostedt
2022-04-23 9:43 ` patrick wang
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=20220420114454.69ab108c@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=frederic@kernel.org \
--cc=jiangshanlai@gmail.com \
--cc=joel@joelfernandes.org \
--cc=josh@joshtriplett.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=patrick.wang.shcn@gmail.com \
--cc=paulmck@kernel.org \
--cc=quic_neeraju@quicinc.com \
--cc=rcu@vger.kernel.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).