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, 108 insertions, 0 deletions

diff --git a/Documentation/arch/arm/setup.rst b/Documentation/arch/arm/setup.rst
new file mode 100644
index 000000000..8e12ef3fb
--- /dev/null
+++ b/Documentation/arch/arm/setup.rst
@@ -0,0 +1,108 @@
+=============================================
+Kernel initialisation parameters on ARM Linux
+=============================================
+
+The following document describes the kernel initialisation parameter
+structure, otherwise known as 'struct param_struct' which is used
+for most ARM Linux architectures.
+
+This structure is used to pass initialisation parameters from the
+kernel loader to the Linux kernel proper, and may be short lived
+through the kernel initialisation process.  As a general rule, it
+should not be referenced outside of arch/arm/kernel/setup.c:setup_arch().
+
+There are a lot of parameters listed in there, and they are described
+below:
+
+ page_size
+   This parameter must be set to the page size of the machine, and
+   will be checked by the kernel.
+
+ nr_pages
+   This is the total number of pages of memory in the system.  If
+   the memory is banked, then this should contain the total number
+   of pages in the system.
+
+   If the system contains separate VRAM, this value should not
+   include this information.
+
+ ramdisk_size
+   This is now obsolete, and should not be used.
+
+ flags
+   Various kernel flags, including:
+
+    =====   ========================
+    bit 0   1 = mount root read only
+    bit 1   unused
+    bit 2   0 = load ramdisk
+    bit 3   0 = prompt for ramdisk
+    =====   ========================
+
+ rootdev
+   major/minor number pair of device to mount as the root filesystem.
+
+ video_num_cols / video_num_rows
+   These two together describe the character size of the dummy console,
+   or VGA console character size.  They should not be used for any other
+   purpose.
+
+   It's generally a good idea to set these to be either standard VGA, or
+   the equivalent character size of your fbcon display.  This then allows
+   all the bootup messages to be displayed correctly.
+
+ video_x / video_y
+   This describes the character position of cursor on VGA console, and
+   is otherwise unused. (should not be used for other console types, and
+   should not be used for other purposes).
+
+ memc_control_reg
+   MEMC chip control register for Acorn Archimedes and Acorn A5000
+   based machines.  May be used differently by different architectures.
+
+ sounddefault
+   Default sound setting on Acorn machines.  May be used differently by
+   different architectures.
+
+ adfsdrives
+   Number of ADFS/MFM disks.  May be used differently by different
+   architectures.
+
+ bytes_per_char_h / bytes_per_char_v
+   These are now obsolete, and should not be used.
+
+ pages_in_bank[4]
+   Number of pages in each bank of the systems memory (used for RiscPC).
+   This is intended to be used on systems where the physical memory
+   is non-contiguous from the processors point of view.
+
+ pages_in_vram
+   Number of pages in VRAM (used on Acorn RiscPC).  This value may also
+   be used by loaders if the size of the video RAM can't be obtained
+   from the hardware.
+
+ initrd_start / initrd_size
+   This describes the kernel virtual start address and size of the
+   initial ramdisk.
+
+ rd_start
+   Start address in sectors of the ramdisk image on a floppy disk.
+
+ system_rev
+   system revision number.
+
+ system_serial_low / system_serial_high
+   system 64-bit serial number
+
+ mem_fclk_21285
+   The speed of the external oscillator to the 21285 (footbridge),
+   which control's the speed of the memory bus, timer & serial port.
+   Depending upon the speed of the cpu its value can be between
+   0-66 MHz. If no params are passed or a value of zero is passed,
+   then a value of 50 Mhz is the default on 21285 architectures.
+
+ paths[8][128]
+   These are now obsolete, and should not be used.
+
+ commandline
+   Kernel command line parameters.  Details can be found elsewhere.