linux-kernel - [PATCH AUTOSEL 6.6 1/6] perf/core: Fix narrow startup race when creating the perf nr_addr

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Date: Mon, 15 Jan 2024 19:08:56 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Greg KH <gregkh@...uxfoundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Sasha Levin <sashal@...nel.org>,
	mingo@...hat.com,
	acme@...nel.org,
	linux-perf-users@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 1/6] perf/core: Fix narrow startup race when creating the perf nr_addr_filters sysfs file

From: Greg KH <gregkh@...uxfoundation.org>

[ Upstream commit 652ffc2104ec1f69dd4a46313888c33527145ccf ]

Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/2023061204-decal-flyable-6090@gregkh
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/events/core.c | 40 ++++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 12 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 58ecb1c24387..f22c540350a1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11413,9 +11413,32 @@ static DEVICE_ATTR_RW(perf_event_mux_interval_ms);
 static struct attribute *pmu_dev_attrs[] = {
 	&dev_attr_type.attr,
 	&dev_attr_perf_event_mux_interval_ms.attr,
+	&dev_attr_nr_addr_filters.attr,
+	NULL,
+};
+
+static umode_t pmu_dev_is_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct pmu *pmu = dev_get_drvdata(dev);
+
+	if (!pmu->nr_addr_filters)
+		return 0;
+
+	return a->mode;
+
+	return 0;
+}
+
+static struct attribute_group pmu_dev_attr_group = {
+	.is_visible = pmu_dev_is_visible,
+	.attrs = pmu_dev_attrs,
+};
+
+static const struct attribute_group *pmu_dev_groups[] = {
+	&pmu_dev_attr_group,
 	NULL,
 };
-ATTRIBUTE_GROUPS(pmu_dev);
 
 static int pmu_bus_running;
 static struct bus_type pmu_bus = {
@@ -11452,18 +11475,11 @@ static int pmu_dev_alloc(struct pmu *pmu)
 	if (ret)
 		goto free_dev;
 
-	/* For PMUs with address filters, throw in an extra attribute: */
-	if (pmu->nr_addr_filters)
-		ret = device_create_file(pmu->dev, &dev_attr_nr_addr_filters);
-
-	if (ret)
-		goto del_dev;
-
-	if (pmu->attr_update)
+	if (pmu->attr_update) {
 		ret = sysfs_update_groups(&pmu->dev->kobj, pmu->attr_update);
-
-	if (ret)
-		goto del_dev;
+		if (ret)
+			goto del_dev;
+	}
 
 out:
 	return ret;
-- 
2.43.0