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, 70 insertions, 0 deletions

diff --git a/Documentation/admin-guide/mono.rst b/Documentation/admin-guide/mono.rst
new file mode 100644
index 000000000..c6dab5680
--- /dev/null
+++ b/Documentation/admin-guide/mono.rst
@@ -0,0 +1,70 @@
+Mono(tm) Binary Kernel Support for Linux
+-----------------------------------------
+
+To configure Linux to automatically execute Mono-based .NET binaries
+(in the form of .exe files) without the need to use the mono CLR
+wrapper, you can use the BINFMT_MISC kernel support.
+
+This will allow you to execute Mono-based .NET binaries just like any
+other program after you have done the following:
+
+1) You MUST FIRST install the Mono CLR support, either by downloading
+   a binary package, a source tarball or by installing from Git. Binary
+   packages for several distributions can be found at:
+
+	https://www.mono-project.com/download/
+
+   Instructions for compiling Mono can be found at:
+
+	https://www.mono-project.com/docs/compiling-mono/linux/
+
+   Once the Mono CLR support has been installed, just check that
+   ``/usr/bin/mono`` (which could be located elsewhere, for example
+   ``/usr/local/bin/mono``) is working.
+
+2) You have to compile BINFMT_MISC either as a module or into
+   the kernel (``CONFIG_BINFMT_MISC``) and set it up properly.
+   If you choose to compile it as a module, you will have
+   to insert it manually with modprobe/insmod, as kmod
+   cannot be easily supported with binfmt_misc.
+   Read the file ``binfmt_misc.txt`` in this directory to know
+   more about the configuration process.
+
+3) Add the following entries to ``/etc/rc.local`` or similar script
+   to be run at system startup:
+
+   .. code-block:: sh
+
+    # Insert BINFMT_MISC module into the kernel
+    if [ ! -e /proc/sys/fs/binfmt_misc/register ]; then
+        /sbin/modprobe binfmt_misc
+	# Some distributions, like Fedora Core, perform
+	# the following command automatically when the
+	# binfmt_misc module is loaded into the kernel
+	# or during normal boot up (systemd-based systems).
+	# Thus, it is possible that the following line
+	# is not needed at all.
+	mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
+    fi
+
+    # Register support for .NET CLR binaries
+    if [ -e /proc/sys/fs/binfmt_misc/register ]; then
+	# Replace /usr/bin/mono with the correct pathname to
+	# the Mono CLR runtime (usually /usr/local/bin/mono
+	# when compiling from sources or CVS).
+        echo ':CLR:M::MZ::/usr/bin/mono:' > /proc/sys/fs/binfmt_misc/register
+    else
+        echo "No binfmt_misc support"
+        exit 1
+    fi
+
+4) Check that ``.exe`` binaries can be ran without the need of a
+   wrapper script, simply by launching the ``.exe`` file directly
+   from a command prompt, for example::
+
+	/usr/bin/xsd.exe
+
+   .. note::
+
+      If this fails with a permission denied error, check
+      that the ``.exe`` file has execute permissions.