linux-kernel - Re: [PATCH 3/3] perf/core: enabling mapping of the stop filters

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Date:	Mon, 18 Jul 2016 14:31:05 +0300
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:	peterz@...radead.org, mingo@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] perf/core: enabling mapping of the stop filters

Mathieu Poirier <mathieu.poirier@...aro.org> writes:

> At this time function perf_addr_filter_needs_mmap() will _not_
> return true on a user space 'stop' filter.  But stop filters
> needs exactly the same kind of mapping that range and start
> filters get.

Indeed.

>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
>  kernel/events/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index b9aa8f0ff070..b0bf00c728c2 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -6498,7 +6498,7 @@ got_name:
>   */
>  static bool perf_addr_filter_needs_mmap(struct perf_addr_filter *filter)
>  {
> -	return filter->filter && filter->inode;
> +	return filter->inode;
>  }

Maybe kill the function altogether and instead:

diff --git a/kernel/events/core.c b/kernel/events/core.c
index a001be5d4b..bc8e1ad170 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7905,7 +7905,8 @@ static void perf_event_addr_filters_apply(struct perf_event *event)
 	list_for_each_entry(filter, &ifh->list, entry) {
 		event->addr_filters_offs[count] = 0;
 
-		if (perf_addr_filter_needs_mmap(filter))
+		/* file-based filter */
+		if (filter->inode)
 			event->addr_filters_offs[count] =
 				perf_addr_filter_apply(filter, mm);

Thanks,
--
Alex