Date: Thu, 26 Jun 2014 18:45:16 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Christopher Covington <cov@codeaurora.org>, Ingo Molnar <mingo@redhat.com>,
        Tom Zanussi <tom.zanussi@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Vagin <avagin@openvz.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Vaibhav Nagarnaik <vnagarnaik@google.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] RFC: Add signal command to trace events
Message-ID: <20140626164516.GA24731@redhat.com>
References: <1403791044-2214-1-git-send-email-cov@codeaurora.org> <20140626111749.3234d4d4@gandalf.local.home> <20140626162943.GA9970@redhat.com>
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On 06/26, Oleg Nesterov wrote:
>
> > > +//ifdef CONFIG_TRACER_SIGNAL
> > > +static void
> > > +signal_trigger(struct event_trigger_data *data)
> > > +{
> > > +	force_sig(SIGSTOP, current);
>
> Well, I don't like this. Imho, it would be nice to avoid signals here.
>
> And SIGSTOP in particular. It can interfere with the "real" SIGSTOP
> sent by user, with ptrace, with tty.

And I forgot to mention, note that SIGSTOP stops the whole thread group,
this is not what we want.

> I think we need something else... "STOP" is actually simple, but we need
> some interface which allows to wakeup a task sleeping in TASK_KILLABLE
> after it hits ETT_FREEZE.

Yes...

Oleg.

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