linux-kernel - [tip:perf/core] x86/perf/intel/cstate: Sanitize error handling

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Date:	Thu, 31 Mar 2016 02:21:24 -0700
From:	tip-bot for Thomas Gleixner <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...hat.com, hpa@...or.com, bp@...e.de, peterz@...radead.org,
	tglx@...utronix.de, torvalds@...ux-foundation.org,
	vincent.weaver@...ne.edu, eranian@...gle.com,
	alexander.shishkin@...ux.intel.com, mingo@...nel.org,
	kan.liang@...el.com, jolsa@...hat.com, linux-kernel@...r.kernel.org
Subject: [tip:perf/core] x86/perf/intel/cstate: Sanitize error handling

Commit-ID:  d29859e7777ebc2c8e2db6e4d8e299f50fc26414
Gitweb:     http://git.kernel.org/tip/d29859e7777ebc2c8e2db6e4d8e299f50fc26414
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 20 Mar 2016 18:59:03 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 31 Mar 2016 10:30:37 +0200

x86/perf/intel/cstate: Sanitize error handling

There is no point in WARN_ON() inside of a well known init function. We
already know the call stack and it's really not of critical importance whether
the registration of a PMU fails.

Aside of that for consistency reasons it's just pointless to try to register
another PMU if the first register attempt failed. There is also no value in
keeping one PMU if the second one can not be registered.

Make it consistent so we can finaly modularize the driver.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Kan Liang <kan.liang@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/20160320185623.579794064@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/intel/cstate.c | 50 +++++++++++++++++++++++-------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/arch/x86/events/intel/cstate.c b/arch/x86/events/intel/cstate.c
index 1aac40f..e90ec9e 100644
--- a/arch/x86/events/intel/cstate.c
+++ b/arch/x86/events/intel/cstate.c
@@ -581,37 +581,45 @@ static int __init cstate_probe(const struct cstate_model *cm)
 	return (has_cstate_core || has_cstate_pkg) ? 0 : -ENODEV;
 }
 
-static void __init cstate_cpumask_init(void)
+static void __init cstate_cleanup(void)
 {
-	int cpu;
-
-	cpu_notifier_register_begin();
-
-	for_each_online_cpu(cpu)
-		cstate_cpu_init(cpu);
+	if (has_cstate_core)
+		perf_pmu_unregister(&cstate_core_pmu);
 
-	__perf_cpu_notifier(cstate_cpu_notifier);
-
-	cpu_notifier_register_done();
+	if (has_cstate_pkg)
+		perf_pmu_unregister(&cstate_pkg_pmu);
 }
 
-static void __init cstate_pmus_register(void)
+static int __init cstate_init(void)
 {
-	int err;
+	int cpu, err;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(cpu)
+		cstate_cpu_init(cpu);
 
 	if (has_cstate_core) {
 		err = perf_pmu_register(&cstate_core_pmu, cstate_core_pmu.name, -1);
-		if (WARN_ON(err))
-			pr_info("Failed to register PMU %s error %d\n",
-				cstate_core_pmu.name, err);
+		if (err) {
+			has_cstate_core = false;
+			pr_info("Failed to register cstate core pmu\n");
+			goto out;
+		}
 	}
 
 	if (has_cstate_pkg) {
 		err = perf_pmu_register(&cstate_pkg_pmu, cstate_pkg_pmu.name, -1);
-		if (WARN_ON(err))
-			pr_info("Failed to register PMU %s error %d\n",
-				cstate_pkg_pmu.name, err);
+		if (err) {
+			has_cstate_pkg = false;
+			pr_info("Failed to register cstate pkg pmu\n");
+			cstate_cleanup();
+			goto out;
+		}
 	}
+	__perf_cpu_notifier(cstate_cpu_notifier);
+out:
+	cpu_notifier_register_done();
+	return err;
 }
 
 static int __init cstate_pmu_init(void)
@@ -630,10 +638,6 @@ static int __init cstate_pmu_init(void)
 	if (err)
 		return err;
 
-	cstate_cpumask_init();
-
-	cstate_pmus_register();
-
-	return 0;
+	return cstate_init();
 }
 device_initcall(cstate_pmu_init);