linux-kernel - Re: [PATCH 2/6] x86,perf/cqm: Fix cqm memory leak and notifier leak

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Date:	Wed,  2 Mar 2016 15:53:59 -0800
From:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
To:	vikas.shivappa@...el.com, vikas.shivappa@...ux.intel.com
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
	tglx@...utronix.de, mingo@...nel.org, peterz@...radead.org,
	ravi.v.shankar@...el.com, tony.luck@...el.com,
	fenghua.yu@...el.com, h.peter.anvin@...el.com
Subject: Re: [PATCH 2/6] x86,perf/cqm: Fix cqm memory leak and notifier leak

Fixes the hotcpu notifier leak and other global variable memory leaks
during cqm(cache quality of service monitoring) initialization.

Reviewed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
---

Fixed the memory leak for cqm_rmid_ptrs as per Thomas feedback.
  
 arch/x86/kernel/cpu/perf_event_intel_cqm.c | 34 ++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
index e6be335..37a93fa 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c
@@ -250,10 +250,13 @@ static int intel_cqm_setup_rmid_cache(void)
 
 	return 0;
 fail:
-	while (r--)
+	while (r--) {
 		kfree(cqm_rmid_ptrs[r]);
+		cqm_rmid_ptrs[r] = NULL;
+	}
 
 	kfree(cqm_rmid_ptrs);
+	cqm_rmid_ptrs = NULL;
 	return -ENOMEM;
 }
 
@@ -1320,9 +1323,19 @@ static const struct x86_cpu_id intel_cqm_match[] = {
 	{}
 };
 
+static void cqm_cleanup(void)
+{
+	int r = cqm_max_rmid;
+
+	while (r--)
+		kfree(cqm_rmid_ptrs[r]);
+
+	kfree(cqm_rmid_ptrs);
+}
+
 static int __init intel_cqm_init(void)
 {
-	char *str, scale[20];
+	char *str = NULL, scale[20];
 	int i, cpu, ret;
 
 	if (!x86_match_cpu(intel_cqm_match))
@@ -1382,16 +1395,25 @@ static int __init intel_cqm_init(void)
 		cqm_pick_event_reader(i);
 	}
 
-	__perf_cpu_notifier(intel_cqm_cpu_notifier);
-
 	ret = perf_pmu_register(&intel_cqm_pmu, "intel_cqm", -1);
-	if (ret)
+	if (ret) {
 		pr_err("Intel CQM perf registration failed: %d\n", ret);
-	else
+		goto out;
+	} else {
 		pr_info("Intel CQM monitoring enabled\n");
+	}
 
+	/*
+	 * Register the hot cpu notifier once we are sure cqm
+	 * is enabled to avoid notifier leak.
+	 */
+	__perf_cpu_notifier(intel_cqm_cpu_notifier);
 out:
 	cpu_notifier_register_done();
+	if (ret) {
+		kfree(str);
+		cqm_cleanup();
+	}
 
 	return ret;
 }
-- 
1.9.1