linux-kernel - [PATCH] perf: qcom_l2_pmu: Make l2_cache_pmu_probe

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Message-Id: <6a0f5bdb6b7b2ed4ef194fc49693e902ad5b95ea.1684397879.git.christophe.jaillet@wanadoo.fr>
Date:   Thu, 18 May 2023 10:18:08 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Neil Leeder <nleeder@...eaurora.org>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] perf: qcom_l2_pmu: Make l2_cache_pmu_probe_cluster() more robust

If an error occurs after calling list_add(), the &l2cache_pmu->clusters
list will reference some memory that will be freed when the managed
resources will be released.

Move the list_add() at the end of the function when everything is in fine.

This is harmless because if l2_cache_pmu_probe_cluster() fails, then
l2_cache_pmu_probe() will fail as well and 'l2cache_pmu' will be released
as well.
But it looks cleaner and could silence static checker warning.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
This is not a fix, because there is no issue.
But in case of interest:
Fixes: 21bdbb7102ed ("perf: add qcom l2 cache perf events driver")
---
 drivers/perf/qcom_l2_pmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/qcom_l2_pmu.c b/drivers/perf/qcom_l2_pmu.c
index aaca6db7d8f6..3f9a98c17a89 100644
--- a/drivers/perf/qcom_l2_pmu.c
+++ b/drivers/perf/qcom_l2_pmu.c
@@ -857,7 +857,6 @@ static int l2_cache_pmu_probe_cluster(struct device *dev, void *data)
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&cluster->next);
-	list_add(&cluster->next, &l2cache_pmu->clusters);
 	cluster->cluster_id = fw_cluster_id;
 
 	irq = platform_get_irq(sdev, 0);
@@ -883,6 +882,7 @@ static int l2_cache_pmu_probe_cluster(struct device *dev, void *data)
 
 	spin_lock_init(&cluster->pmu_lock);
 
+	list_add(&cluster->next, &l2cache_pmu->clusters);
 	l2cache_pmu->num_pmus++;
 
 	return 0;
-- 
2.34.1