linux-kernel - [PATCH 4.18 01/44] perf/core: Add sanity check to deal with pinned event failure

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Message-Id: <20181011152452.621609204@linuxfoundation.org>
Date:   Thu, 11 Oct 2018 17:39:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>, fenghua.yu@...el.com,
        tony.luck@...el.com, acme@...nel.org, gavin.hindman@...el.com,
        jithu.joseph@...el.com, dave.hansen@...el.com, hpa@...or.com
Subject: [PATCH 4.18 01/44] perf/core: Add sanity check to deal with pinned event failure

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Reinette Chatre <reinette.chatre@...el.com>

commit befb1b3c2703897c5b8ffb0044dc5d0e5f27c5d7 upstream.

It is possible that a failure can occur during the scheduling of a
pinned event. The initial portion of perf_event_read_local() contains
the various error checks an event should pass before it can be
considered valid. Ensure that the potential scheduling failure
of a pinned event is checked for and have a credible error.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: fenghua.yu@...el.com
Cc: tony.luck@...el.com
Cc: acme@...nel.org
Cc: gavin.hindman@...el.com
Cc: jithu.joseph@...el.com
Cc: dave.hansen@...el.com
Cc: hpa@...or.com
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/6486385d1f30336e9973b24c8c65f5079543d3d3.1537377064.git.reinette.chatre@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/events/core.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3940,6 +3940,12 @@ int perf_event_read_local(struct perf_ev
 		goto out;
 	}
 
+	/* If this is a pinned event it must be running on this CPU */
+	if (event->attr.pinned && event->oncpu != smp_processor_id()) {
+		ret = -EBUSY;
+		goto out;
+	}
+
 	/*
 	 * If the event is currently on this CPU, its either a per-task event,
 	 * or local to this CPU. Furthermore it means its ACTIVE (otherwise