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From: Ingo Molnar <mingo@elte.hu>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	perfmon2-devel@lists.sf.net, paulus@samba.org,
	davem@davemloft.net
Subject: Re: [PATCH] perf_events: fix cgrp stale pointer in update_cgrp_time_from_cpuctx()
Date: Wed, 23 Mar 2011 12:36:01 +0100	[thread overview]
Message-ID: <20110323113601.GA27809@elte.hu> (raw)
In-Reply-To: <20110321151126.GA5084@quad>


* Stephane Eranian <eranian@google.com> wrote:

> -	if (is_cgroup_event(event))
> +	if (is_cgroup_event(event)) {
>  		ctx->nr_cgroups--;
> +		cpuctx = __get_cpu_context(ctx);
> +		/*
> +		 * if there are no more cgroup events
> +		 * then clear cgrp to avoid stale pointer
> +		 * in update_cgrp_time_from_cpuctx()
> +		 */
> +		if (!ctx->nr_cgroups)
> +			cpuctx->cgrp = NULL;
> +	}

The ->cgrp pointer does not exist on !CGROUPS kernels. I suspect the cleanest 
approach would be to make those two cgrp fields available unconditionally in 
struct perf_event.

Thanks,

	Ingo

  reply	other threads:[~2011-03-23 11:36 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-21 15:11 Stephane Eranian
2011-03-23 11:36 ` Ingo Molnar [this message]
2011-03-23 12:47   ` Stephane Eranian

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