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Date: Wed, 31 Jul 2013 23:40:00 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@...hat.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
Jiri Olsa <jolsa@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC][PATCH 4/4] tracing/uprobes: Fail to unregister if probe
event files are open
Srikar,
Can you give your Acked-by to this patch.
Thanks!
-- Steve
On Wed, 2013-07-03 at 23:33 -0400, Steven Rostedt wrote:
> plain text document attachment
> (0004-tracing-uprobes-Fail-to-unregister-if-probe-event-fi.patch)
> From: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
>
> When one of the event files is opened, we need to prevent them from
> being removed. Modules do with with the module owner set (automated
> from the VFS layer). The ftrace buffer instances have a ref count added
> to the trace_array when the enabled file is opened (the others are not
> that big of a deal, as they only reference the event calls which
> still exist when an instance disappears). But kprobes and uprobes
> do not have any protection.
>
> Have the unregister probe fail when the event files are open, in use
> are used by perf.
>
> Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
> ---
> kernel/trace/trace_uprobe.c | 48 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index d5d0cd3..4916da5 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -70,7 +70,7 @@ struct trace_uprobe {
> (sizeof(struct probe_arg) * (n)))
>
> static int register_uprobe_event(struct trace_uprobe *tu);
> -static void unregister_uprobe_event(struct trace_uprobe *tu);
> +static int unregister_uprobe_event(struct trace_uprobe *tu);
>
> static DEFINE_MUTEX(uprobe_lock);
> static LIST_HEAD(uprobe_list);
> @@ -164,11 +164,17 @@ static struct trace_uprobe *find_probe_event(const char *event, const char *grou
> }
>
> /* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
> -static void unregister_trace_uprobe(struct trace_uprobe *tu)
> +static int unregister_trace_uprobe(struct trace_uprobe *tu)
> {
> + int ret;
> +
> + ret = unregister_uprobe_event(tu);
> + if (ret)
> + return ret;
> +
> list_del(&tu->list);
> - unregister_uprobe_event(tu);
> free_trace_uprobe(tu);
> + return 0;
> }
>
> /* Register a trace_uprobe and probe_event */
> @@ -181,9 +187,12 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
>
> /* register as an event */
> old_tp = find_probe_event(tu->call.name, tu->call.class->system);
> - if (old_tp)
> + if (old_tp) {
> /* delete old event */
> - unregister_trace_uprobe(old_tp);
> + ret = unregister_trace_uprobe(old_tp);
> + if (ret)
> + goto end;
> + }
>
> ret = register_uprobe_event(tu);
> if (ret) {
> @@ -256,6 +265,8 @@ static int create_trace_uprobe(int argc, char **argv)
> group = UPROBE_EVENT_SYSTEM;
>
> if (is_delete) {
> + int ret;
> +
> if (!event) {
> pr_info("Delete command needs an event name.\n");
> return -EINVAL;
> @@ -269,9 +280,9 @@ static int create_trace_uprobe(int argc, char **argv)
> return -ENOENT;
> }
> /* delete an event */
> - unregister_trace_uprobe(tu);
> + ret = unregister_trace_uprobe(tu);
> mutex_unlock(&uprobe_lock);
> - return 0;
> + return ret;
> }
>
> if (argc < 2) {
> @@ -408,16 +419,20 @@ fail_address_parse:
> return ret;
> }
>
> -static void cleanup_all_probes(void)
> +static int cleanup_all_probes(void)
> {
> struct trace_uprobe *tu;
> + int ret = 0;
>
> mutex_lock(&uprobe_lock);
> while (!list_empty(&uprobe_list)) {
> tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
> - unregister_trace_uprobe(tu);
> + ret = unregister_trace_uprobe(tu);
> + if (ret)
> + break;
> }
> mutex_unlock(&uprobe_lock);
> + return ret;
> }
>
> /* Probes listing interfaces */
> @@ -462,8 +477,12 @@ static const struct seq_operations probes_seq_op = {
>
> static int probes_open(struct inode *inode, struct file *file)
> {
> + int ret = 0;
> +
> if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC))
> - cleanup_all_probes();
> + ret = cleanup_all_probes();
> + if (ret)
> + return ret;
>
> return seq_open(file, &probes_seq_op);
> }
> @@ -970,12 +989,17 @@ static int register_uprobe_event(struct trace_uprobe *tu)
> return ret;
> }
>
> -static void unregister_uprobe_event(struct trace_uprobe *tu)
> +static int unregister_uprobe_event(struct trace_uprobe *tu)
> {
> + int ret;
> +
> /* tu->event is unregistered in trace_remove_event_call() */
> - trace_remove_event_call(&tu->call);
> + ret = trace_remove_event_call(&tu->call);
> + if (ret)
> + return ret;
> kfree(tu->call.print_fmt);
> tu->call.print_fmt = NULL;
> + return 0;
> }
>
> /* Make a trace interface for controling probe points */
--
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