linux-kernel - Re: [PATCH 4/4][RFC] perf_counter: Allow sharing of output channels

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]

Date:	Wed, 19 Aug 2009 18:24:28 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mike Galbraith <efault@....de>, linux-kernel@...r.kernel.org,
	stephane eranian <eranian@...glemail.com>
Subject: Re: [PATCH 4/4][RFC] perf_counter: Allow sharing of output channels

On Wed, 2009-08-19 at 18:19 +0200, Frederic Weisbecker wrote:
> On Wed, Aug 19, 2009 at 11:18:27AM +0200, Peter Zijlstra wrote:
> > Provide the ability to configure a counter to send its output to
> > another (already existing) counter's output stream.
> > 
> > [ compile tested only ]
> > 
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> > Cc: stephane eranian <eranian@...glemail.com>
> > +int perf_counter_set_output(struct perf_counter *counter, int output_fd)
> > +{
> > +	struct perf_counter *output_counter = NULL;
> > +	struct file *output_file = NULL;
> > +	struct perf_counter *old_output;
> > +	int fput_needed = 0;
> > +	int ret = -EINVAL;
> > +
> > +	if (!output_fd)
> > +		goto set;
> > +
> > +	output_file = fget_light(output_fd, &fput_needed);
> > +	if (!output_file)
> > +		return -EBADF;
> > +
> > +	if (output_file->f_op != &perf_fops)
> > +		goto out;
> > +
> > +	output_counter = output_file->private_data;
> > +
> > +	/* Don't chain output fds */
> > +	if (output_counter->output)
> > +		goto out;
> 
> 
> 
> If you don't chain them, how do you propagate more than one
> path of output redirected?

you mean, fd2->fd1->fd0 ?

You don't, that sounds like a silly thing to do, do fd1->fd0, fd2->fd0
instead.

--
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/