[PATCH 2/3] perf/arm_cspmu: nvidia: handle empty resource list in PCIE-TGT init

[Saurav Sachidanand <sauravsc@amazon.com>]

When acpi_dev_get_memory_resources() returns success but the resource
list is empty (rentry is NULL), addr_filter_reg remains NULL from
devm_kzalloc. Since IS_ERR(NULL) is false, the function proceeds
without error and later dereferences the NULL pointer in
pcie_tgt_pmu_config_addr_filter().

Set addr_filter_reg to ERR_PTR(-ENODEV) when the resource list is
empty so the existing IS_ERR check catches it.

Fixes: 3dd73022306b ("perf/arm_cspmu: nvidia: Add Tegra410 PCIE-TGT PMU")
Signed-off-by: Saurav Sachidanand <sauravsc@amazon.com>
---
 drivers/perf/arm_cspmu/nvidia_cspmu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/perf/arm_cspmu/nvidia_cspmu.c b/drivers/perf/arm_cspmu/nvidia_cspmu.c
index bac83e424d6dc..bae722e263e91 100644
--- a/drivers/perf/arm_cspmu/nvidia_cspmu.c
+++ b/drivers/perf/arm_cspmu/nvidia_cspmu.c
@@ -555,14 +555,16 @@ static int pcie_tgt_init_data(struct arm_cspmu *cspmu)
 
 	rentry = list_first_entry_or_null(
 		&resource_list, struct resource_entry, node);
-	if (rentry) {
+	if (rentry)
 		data->addr_filter_reg = devm_ioremap_resource(dev, rentry->res);
-		ret = 0;
-	}
+	else
+		data->addr_filter_reg = ERR_PTR(-ENODEV);
 
 	if (IS_ERR(data->addr_filter_reg)) {
 		dev_err(dev, "failed to get address filter resource\n");
 		ret = PTR_ERR(data->addr_filter_reg);
+	} else {
+		ret = 0;
 	}
 
 	acpi_dev_free_resource_list(&resource_list);
-- 
2.47.3