[PATCH AUTOSEL 6.13 08/16] perf: arm_pmu: Don't disable counter in armpmu_add()

[PATCH AUTOSEL 6.13 08/16] perf: arm_pmu: Don't disable counter in armpmu_add()

[Sasha Levin]

From: Mark Rutland <mark.rutland@arm.com>

[ Upstream commit dcca27bc1eccb9abc2552aab950b18a9742fb8e7 ]

Currently armpmu_add() tries to handle a newly-allocated counter having
a stale associated event, but this should not be possible, and if this
were to happen the current mitigation is insufficient and potentially
expensive. It would be better to warn if we encounter the impossible
case.

Calls to pmu::add() and pmu::del() are serialized by the core perf code,
and armpmu_del() clears the relevant slot in pmu_hw_events::events[]
before clearing the bit in pmu_hw_events::used_mask such that the
counter can be reallocated. Thus when armpmu_add() allocates a counter
index from pmu_hw_events::used_mask, it should not be possible to observe
a stale even in pmu_hw_events::events[] unless either
pmu_hw_events::used_mask or pmu_hw_events::events[] have been corrupted.

If this were to happen, we'd end up with two events with the same
event->hw.idx, which would clash with each other during reprogramming,
deletion, etc, and produce bogus results. Add a WARN_ON_ONCE() for this
case so that we can detect if this ever occurs in practice.

That possiblity aside, there's no need to call arm_pmu::disable(event)
for the new event. The PMU reset code initialises the counter in a
disabled state, and armpmu_del() will disable the counter before it can
be reused. Remove the redundant disable.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Tested-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250218-arm-brbe-v19-v20-2-4e9922fc2e8e@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/perf/arm_pmu.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 398cce3d76fc4..2f33e69a8caf2 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -342,12 +342,10 @@ armpmu_add(struct perf_event *event, int flags)
 	if (idx < 0)
 		return idx;
 
-	/*
-	 * If there is an event in the counter we are going to use then make
-	 * sure it is disabled.
-	 */
+	/* The newly-allocated counter should be empty */
+	WARN_ON_ONCE(hw_events->events[idx]);
+
 	event->hw.idx = idx;
-	armpmu->disable(event);
 	hw_events->events[idx] = event;
 
 	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
-- 
2.39.5

[PATCH AUTOSEL 6.13 09/16] perf/dwc_pcie: fix some unreleased resources

[Sasha Levin]

From: Yunhui Cui <cuiyunhui@bytedance.com>

[ Upstream commit 6eb1e8ef586ac4a3dcdc20248f9cb45e4ceb141f ]

Release leaked resources, such as plat_dev and dev_info.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Reviewed-by: Shuai Xue <xueshuai@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250220121716.50324-2-cuiyunhui@bytedance.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/perf/dwc_pcie_pmu.c | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
index 9cbea9675e21a..a7e7864e73a8e 100644
--- a/drivers/perf/dwc_pcie_pmu.c
+++ b/drivers/perf/dwc_pcie_pmu.c
@@ -567,8 +567,10 @@ static int dwc_pcie_register_dev(struct pci_dev *pdev)
 		return PTR_ERR(plat_dev);
 
 	dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
-	if (!dev_info)
+	if (!dev_info) {
+		platform_device_unregister(plat_dev);
 		return -ENOMEM;
+	}
 
 	/* Cache platform device to handle pci device hotplug */
 	dev_info->plat_dev = plat_dev;
@@ -724,6 +726,15 @@ static struct platform_driver dwc_pcie_pmu_driver = {
 	.driver = {.name = "dwc_pcie_pmu",},
 };
 
+static void dwc_pcie_cleanup_devices(void)
+{
+	struct dwc_pcie_dev_info *dev_info, *tmp;
+
+	list_for_each_entry_safe(dev_info, tmp, &dwc_pcie_dev_info_head, dev_node) {
+		dwc_pcie_unregister_dev(dev_info);
+	}
+}
+
 static int __init dwc_pcie_pmu_init(void)
 {
 	struct pci_dev *pdev = NULL;
@@ -736,7 +747,7 @@ static int __init dwc_pcie_pmu_init(void)
 		ret = dwc_pcie_register_dev(pdev);
 		if (ret) {
 			pci_dev_put(pdev);
-			return ret;
+			goto err_cleanup;
 		}
 	}
 
@@ -745,35 +756,35 @@ static int __init dwc_pcie_pmu_init(void)
 				      dwc_pcie_pmu_online_cpu,
 				      dwc_pcie_pmu_offline_cpu);
 	if (ret < 0)
-		return ret;
+		goto err_cleanup;
 
 	dwc_pcie_pmu_hp_state = ret;
 
 	ret = platform_driver_register(&dwc_pcie_pmu_driver);
 	if (ret)
-		goto platform_driver_register_err;
+		goto err_remove_cpuhp;
 
 	ret = bus_register_notifier(&pci_bus_type, &dwc_pcie_pmu_nb);
 	if (ret)
-		goto platform_driver_register_err;
+		goto err_unregister_driver;
 	notify = true;
 
 	return 0;
 
-platform_driver_register_err:
+err_unregister_driver:
+	platform_driver_unregister(&dwc_pcie_pmu_driver);
+err_remove_cpuhp:
 	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
-
+err_cleanup:
+	dwc_pcie_cleanup_devices();
 	return ret;
 }
 
 static void __exit dwc_pcie_pmu_exit(void)
 {
-	struct dwc_pcie_dev_info *dev_info, *tmp;
-
 	if (notify)
 		bus_unregister_notifier(&pci_bus_type, &dwc_pcie_pmu_nb);
-	list_for_each_entry_safe(dev_info, tmp, &dwc_pcie_dev_info_head, dev_node)
-		dwc_pcie_unregister_dev(dev_info);
+	dwc_pcie_cleanup_devices();
 	platform_driver_unregister(&dwc_pcie_pmu_driver);
 	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
 }
-- 
2.39.5