From: Steven Rostedt <rostedt@goodmis.org>
To: Alexei Starovoitov <ast@fb.com>
Cc: Dave Jones <davej@codemonkey.org.uk>,
Martin KaFai Lau <kafai@fb.com>, <linux-kernel@vger.kernel.org>,
<kernel-team@fb.com>
Subject: Re: [PATCH] tracing: ignore FTRACE_FL_DISABLED while walking dyn_ftrace records
Date: Mon, 14 Nov 2016 14:24:28 -0500 [thread overview]
Message-ID: <20161114142428.1091961b@gandalf.local.home> (raw)
In-Reply-To: <1478560460-3818619-1-git-send-email-ast@fb.com>
On Mon, 7 Nov 2016 15:14:20 -0800
Alexei Starovoitov <ast@fb.com> wrote:
> ftrace_shutdown() checks for sanity of ftrace records
> and if dyn_ftrace->flags is not zero, it will warn.
> It can happen that 'flags' are set to FTRACE_FL_DISABLED at this point,
> since some module was loaded, but before ftrace_module_enable()
> cleared the flags for this module.
>
> In other words the module.c is doing:
> ftrace_module_init(mod); // calls ftrace_update_code() that sets flags=FTRACE_FL_DISABLED
> ... // here ftrace_shutdown() is called that warns, since
> err = prepare_coming_module(mod); // didn't have a chance to clear FTRACE_FL_DISABLED
>
> Fix it by ignoring disabled records.
> It's similar to what __ftrace_hash_rec_update() is already doing.
>
Alexei,
Do you have a clear reproducer of this bug?
-- Steve
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
> kernel/trace/ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 2050a7652a86..326498baab83 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2763,7 +2763,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
> struct dyn_ftrace *rec;
>
> do_for_each_ftrace_rec(pg, rec) {
> - if (FTRACE_WARN_ON_ONCE(rec->flags))
> + if (FTRACE_WARN_ON_ONCE(rec->flags & ~FTRACE_FL_DISABLED))
> pr_warn(" %pS flags:%lx\n",
> (void *)rec->ip, rec->flags);
> } while_for_each_ftrace_rec();
next prev parent reply other threads:[~2016-11-14 19:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-07 23:14 [PATCH] tracing: ignore FTRACE_FL_DISABLED while walking dyn_ftrace records Alexei Starovoitov
2016-11-14 19:24 ` Steven Rostedt [this message]
2016-11-14 20:30 ` Alexei Starovoitov
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=20161114142428.1091961b@gandalf.local.home \
--to=rostedt@goodmis.org \
--cc=ast@fb.com \
--cc=davej@codemonkey.org.uk \
--cc=kafai@fb.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@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).