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, 111 insertions, 0 deletions

diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
new file mode 100644
index 000000000..f4058e8e9
--- /dev/null
+++ b/Documentation/trace/index.rst
@@ -0,0 +1,111 @@
+================================
+Linux Tracing Technologies Guide
+================================
+
+Tracing in the Linux kernel is a powerful mechanism that allows
+developers and system administrators to analyze and debug system
+behavior. This guide provides documentation on various tracing
+frameworks and tools available in the Linux kernel.
+
+Introduction to Tracing
+-----------------------
+
+This section provides an overview of Linux tracing mechanisms
+and debugging approaches.
+
+.. toctree::
+   :maxdepth: 1
+
+   debugging
+   tracepoints
+   tracepoint-analysis
+   ring-buffer-map
+
+Core Tracing Frameworks
+-----------------------
+
+The following are the primary tracing frameworks integrated into
+the Linux kernel.
+
+.. toctree::
+   :maxdepth: 1
+
+   ftrace
+   ftrace-design
+   ftrace-uses
+   kprobes
+   kprobetrace
+   fprobetrace
+   eprobetrace
+   fprobe
+   ring-buffer-design
+
+Event Tracing and Analysis
+--------------------------
+
+A detailed explanation of event tracing mechanisms and their
+applications.
+
+.. toctree::
+   :maxdepth: 1
+
+   events
+   events-kmem
+   events-power
+   events-nmi
+   events-msr
+   events-landlock
+   events-pci
+   events-pci-controller
+   boottime-trace
+   histogram
+   histogram-design
+
+Hardware and Performance Tracing
+--------------------------------
+
+This section covers tracing features that monitor hardware
+interactions and system performance.
+
+.. toctree::
+   :maxdepth: 1
+
+   intel_th
+   stm
+   sys-t
+   coresight/index
+   rv/index
+   hisi-ptt
+   mmiotrace
+   hwlat_detector
+   osnoise-tracer
+   timerlat-tracer
+
+User-Space Tracing
+------------------
+
+These tools allow tracing user-space applications and
+interactions.
+
+.. toctree::
+   :maxdepth: 1
+
+   user_events
+   uprobetracer
+
+Remote Tracing
+--------------
+
+This section covers the framework to read compatible ring-buffers, written by
+entities outside of the kernel (most likely firmware or hypervisor)
+
+.. toctree::
+   :maxdepth: 1
+
+   remotes
+
+Additional Resources
+--------------------
+
+For more details, refer to the respective documentation of each
+tracing tool and framework.