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, 60 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-kernel-irq b/Documentation/ABI/testing/sysfs-kernel-irq
new file mode 100644
index 000000000..8910d0c4b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-irq
@@ -0,0 +1,60 @@
+What:		/sys/kernel/irq
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	Directory containing information about the system's IRQs.
+		Specifically, data from the associated struct irq_desc.
+		The information here is similar to that in /proc/interrupts
+		but in a more machine-friendly format.  This directory contains
+		one subdirectory for each Linux IRQ number.
+
+What:		/sys/kernel/irq/<irq>/actions
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	The IRQ action chain.  A comma-separated list of zero or more
+		device names associated with this interrupt.
+
+What:		/sys/kernel/irq/<irq>/chip_name
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	Human-readable chip name supplied by the associated device
+		driver.
+
+What:		/sys/kernel/irq/<irq>/hwirq
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	When interrupt translation domains are used, this file contains
+		the underlying hardware IRQ number used for this Linux IRQ.
+
+What:		/sys/kernel/irq/<irq>/name
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	Human-readable flow handler name as defined by the irq chip
+		driver.
+
+What:		/sys/kernel/irq/<irq>/per_cpu_count
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	The number of times the interrupt has fired since boot.  This
+		is a comma-separated list of counters; one per CPU in CPU id
+		order.  NOTE: This file consistently shows counters for all
+		CPU ids.  This differs from the behavior of /proc/interrupts
+		which only shows counters for online CPUs.
+
+What:		/sys/kernel/irq/<irq>/type
+Date:		September 2016
+KernelVersion:	4.9
+Contact:	Craig Gallek <kraig@google.com>
+Description:	The type of the interrupt.  Either the string 'level' or 'edge'.
+
+What:		/sys/kernel/irq/<irq>/wakeup
+Date:		March 2018
+KernelVersion:	4.17
+Contact:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Description:	The wakeup state of the interrupt. Either the string
+		'enabled' or 'disabled'.