linux-kernel - [PATCH v3] cpufreq: cppc: Set fie_disabled to FIE_DISABLED if fails to create kworker

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Date:   Thu, 17 Aug 2023 07:47:56 +0000
From:   Liao Chang <liaochang1@...wei.com>
To:     <rafael@...nel.org>, <viresh.kumar@...aro.org>
CC:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] cpufreq: cppc: Set fie_disabled to FIE_DISABLED if fails to create kworker_fie

The function cppc_freq_invariance_init() may failed to create
kworker_fie, make it more robust by setting fie_disabled to FIE_DISBALED
to prevent an invalid pointer dereference in kthread_destroy_worker(),
which called from cppc_freq_invariance_exit().

v3:
Simplify cleanup code when invariance initialization fails.

v2:
Set fie_disabled to FIE_DISABLED when invariance initialization fails.

Link: https://lore.kernel.org/all/20230816034630.a4hvsj373q6aslk3@vireshk-i7/

Signed-off-by: Liao Chang <liaochang1@...wei.com>
---
 drivers/cpufreq/cppc_cpufreq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 022e3555407c..4d501f0bf55d 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -249,15 +249,19 @@ static void __init cppc_freq_invariance_init(void)
 		return;
 
 	kworker_fie = kthread_create_worker(0, "cppc_fie");
-	if (IS_ERR(kworker_fie))
+	if (IS_ERR(kworker_fie)) {
+		pr_warn("%s: failed to create kworker_fie: %ld\n", __func__,
+			PTR_ERR(kworker_fie));
+		fie_disabled = FIE_DISABLED;
 		return;
+	}
 
 	ret = sched_setattr_nocheck(kworker_fie->task, &attr);
 	if (ret) {
 		pr_warn("%s: failed to set SCHED_DEADLINE: %d\n", __func__,
 			ret);
 		kthread_destroy_worker(kworker_fie);
-		return;
+		fie_disabled = FIE_DISABLED;
 	}
 }
 
@@ -267,7 +271,6 @@ static void cppc_freq_invariance_exit(void)
 		return;
 
 	kthread_destroy_worker(kworker_fie);
-	kworker_fie = NULL;
 }
 
 #else
-- 
2.34.1