[PATCH 6.6 013/322] perf/core: Fix narrow startup race when creating the perf nr_addr_filters sysfs file

Greg Kroah-Hartman
2024-02-03T04:11:32Z

From: Greg KH <gregkh@linuxfoundation.org>

[ Upstream commit 652ffc2104ec1f69dd4a46313888c33527145ccf ]

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/2023061204-decal-flyable-6090@gregkh
Signed-off-by: Sasha Levin <sashal@kernel.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