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, 103 insertions, 0 deletions

diff --git a/drivers/bus/fsl-mc/obj-api.c b/drivers/bus/fsl-mc/obj-api.c
new file mode 100644
index 000000000..06c1dd84e
--- /dev/null
+++ b/drivers/bus/fsl-mc/obj-api.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/*
+ * Copyright 2021 NXP
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/fsl/mc.h>
+
+#include "fsl-mc-private.h"
+
+static int fsl_mc_get_open_cmd_id(const char *type)
+{
+	static const struct {
+		int cmd_id;
+		const char *type;
+	} dev_ids[] = {
+		{ DPRTC_CMDID_OPEN, "dprtc" },
+		{ DPRC_CMDID_OPEN, "dprc" },
+		{ DPNI_CMDID_OPEN, "dpni" },
+		{ DPIO_CMDID_OPEN, "dpio" },
+		{ DPSW_CMDID_OPEN, "dpsw" },
+		{ DPBP_CMDID_OPEN, "dpbp" },
+		{ DPCON_CMDID_OPEN, "dpcon" },
+		{ DPMCP_CMDID_OPEN, "dpmcp" },
+		{ DPMAC_CMDID_OPEN, "dpmac" },
+		{ DPSECI_CMDID_OPEN, "dpseci" },
+		{ DPDMUX_CMDID_OPEN, "dpdmux" },
+		{ DPDCEI_CMDID_OPEN, "dpdcei" },
+		{ DPAIOP_CMDID_OPEN, "dpaiop" },
+		{ DPCI_CMDID_OPEN, "dpci" },
+		{ DPDMAI_CMDID_OPEN, "dpdmai" },
+		{ DPDBG_CMDID_OPEN, "dpdbg" },
+		{ 0, NULL }
+	};
+	int i;
+
+	for (i = 0; dev_ids[i].type; i++)
+		if (!strcmp(dev_ids[i].type, type))
+			return dev_ids[i].cmd_id;
+
+	return -1;
+}
+
+int fsl_mc_obj_open(struct fsl_mc_io *mc_io,
+		    u32 cmd_flags,
+		    int obj_id,
+		    char *obj_type,
+		    u16 *token)
+{
+	struct fsl_mc_command cmd = { 0 };
+	struct fsl_mc_obj_cmd_open *cmd_params;
+	int err = 0;
+	int cmd_id = fsl_mc_get_open_cmd_id(obj_type);
+
+	if (cmd_id == -1)
+		return -ENODEV;
+
+	/* prepare command */
+	cmd.header = mc_encode_cmd_header(cmd_id, cmd_flags, 0);
+	cmd_params = (struct fsl_mc_obj_cmd_open *)cmd.params;
+	cmd_params->obj_id = cpu_to_le32(obj_id);
+
+	/* send command to mc*/
+	err = mc_send_command(mc_io, &cmd);
+	if (err)
+		return err;
+
+	/* retrieve response parameters */
+	*token = mc_cmd_hdr_read_token(&cmd);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(fsl_mc_obj_open);
+
+int fsl_mc_obj_close(struct fsl_mc_io *mc_io,
+		     u32 cmd_flags,
+		     u16 token)
+{
+	struct fsl_mc_command cmd = { 0 };
+
+	/* prepare command */
+	cmd.header = mc_encode_cmd_header(OBJ_CMDID_CLOSE, cmd_flags,
+					  token);
+
+	/* send command to mc*/
+	return mc_send_command(mc_io, &cmd);
+}
+EXPORT_SYMBOL_GPL(fsl_mc_obj_close);
+
+int fsl_mc_obj_reset(struct fsl_mc_io *mc_io,
+		     u32 cmd_flags,
+		     u16 token)
+{
+	struct fsl_mc_command cmd = { 0 };
+
+	/* prepare command */
+	cmd.header = mc_encode_cmd_header(OBJ_CMDID_RESET, cmd_flags,
+					  token);
+
+	/* send command to mc*/
+	return mc_send_command(mc_io, &cmd);
+}
+EXPORT_SYMBOL_GPL(fsl_mc_obj_reset);