linux-kernel - [PATCH] perf/x86/intel/uncore: fix wrong box pointer check

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Message-Id: <20170629190926.2456-1-kan.liang@intel.com>
Date:   Thu, 29 Jun 2017 12:09:26 -0700
From:   kan.liang@...el.com
To:     tglx@...utronix.de, mingo@...hat.com
Cc:     linux-kernel@...r.kernel.org, Kan Liang <kan.liang@...el.com>
Subject: [PATCH] perf/x86/intel/uncore: fix wrong box pointer check

From: Kan Liang <kan.liang@...el.com>

Should not init a NULL box. It will cause system crash.
The issue looks like caused by a typo. It is introduced from:

commit fff4b87e594a ("perf/x86/intel/uncore: Make package handling
more robust")

This was not noticed because there is no NULL box. Also, for most
boxes, they are enabled by default. The init code is not critical.

Signed-off-by: Kan Liang <kan.liang@...el.com>
---
 arch/x86/events/intel/uncore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 758c1aa5009d..44ec523287f6 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -1170,7 +1170,7 @@ static int uncore_event_cpu_online(unsigned int cpu)
 		pmu = type->pmus;
 		for (i = 0; i < type->num_boxes; i++, pmu++) {
 			box = pmu->boxes[pkg];
-			if (!box && atomic_inc_return(&box->refcnt) == 1)
+			if (box && atomic_inc_return(&box->refcnt) == 1)
 				uncore_box_init(box);
 		}
 	}
-- 
2.11.0