linux-kernel - Re: ftrace multibuffer && rcu (Was: tracing/uprobes: Support ftrace_event

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130614161837.GA15268@redhat.com>
Date:	Fri, 14 Jun 2013 18:18:37 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: ftrace multibuffer && rcu (Was: tracing/uprobes: Support
	ftrace_event_file base multibuffer)

On 06/14, Oleg Nesterov wrote:
>
> So perhaps something like below (untested) makes sense? With this patch
> we can trivially convert trace_kprobe.c to use list_add/del/each_rcu.

Forgot to mention, the patch is obviously incomplete, __kprobe_trace_func()
can see the "dead" file even if its memory can't go away. But this looks
fixable.

> +static inline struct event_file_link *
> +alloc_event_file_link(struct ftrace_event_file *file)
> +{
> +	struct event_file_link *link = kmalloc(sizeof(*link), GFP_KERNEL);
> +	if (link)
> +		link->file = file;
> +	return link;
> +}

And this lacks atomic_inc(file->refcnt).

In short, this is just to explain what I meant, the actual change should
probably differ.

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/