x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 100 insertions, 0 deletions

diff --git a/drivers/clk/mmp/reset.c b/drivers/clk/mmp/reset.c
new file mode 100644
index 000000000..1e4e105ef
--- /dev/null
+++ b/drivers/clk/mmp/reset.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/reset-controller.h>
+
+#include "reset.h"
+
+#define rcdev_to_unit(rcdev) container_of(rcdev, struct mmp_clk_reset_unit, rcdev)
+
+static int mmp_of_reset_xlate(struct reset_controller_dev *rcdev,
+			  const struct of_phandle_args *reset_spec)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	int i;
+
+	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
+		return -EINVAL;
+
+	for (i = 0; i < rcdev->nr_resets; i++) {
+		cell = &unit->cells[i];
+		if (cell->clk_id == reset_spec->args[0])
+			break;
+	}
+
+	if (i == rcdev->nr_resets)
+		return -EINVAL;
+
+	return i;
+}
+
+static int mmp_clk_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	unsigned long flags = 0;
+	u32 val;
+
+	cell = &unit->cells[id];
+	if (cell->lock)
+		spin_lock_irqsave(cell->lock, flags);
+
+	val = readl(cell->reg);
+	val |= cell->bits;
+	writel(val, cell->reg);
+
+	if (cell->lock)
+		spin_unlock_irqrestore(cell->lock, flags);
+
+	return 0;
+}
+
+static int mmp_clk_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	unsigned long flags = 0;
+	u32 val;
+
+	cell = &unit->cells[id];
+	if (cell->lock)
+		spin_lock_irqsave(cell->lock, flags);
+
+	val = readl(cell->reg);
+	val &= ~cell->bits;
+	writel(val, cell->reg);
+
+	if (cell->lock)
+		spin_unlock_irqrestore(cell->lock, flags);
+
+	return 0;
+}
+
+static const struct reset_control_ops mmp_clk_reset_ops = {
+	.assert		= mmp_clk_reset_assert,
+	.deassert	= mmp_clk_reset_deassert,
+};
+
+void mmp_clk_reset_register(struct device_node *np,
+			struct mmp_clk_reset_cell *cells, int nr_resets)
+{
+	struct mmp_clk_reset_unit *unit;
+
+	unit = kzalloc_obj(*unit);
+	if (!unit)
+		return;
+
+	unit->cells = cells;
+	unit->rcdev.of_reset_n_cells = 1;
+	unit->rcdev.nr_resets = nr_resets;
+	unit->rcdev.ops = &mmp_clk_reset_ops;
+	unit->rcdev.of_node = np;
+	unit->rcdev.of_xlate = mmp_of_reset_xlate;
+
+	reset_controller_register(&unit->rcdev);
+}