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, 91 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-driver-genwqe b/Documentation/ABI/testing/debugfs-driver-genwqe
new file mode 100644
index 000000000..b45b01654
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-driver-genwqe
@@ -0,0 +1,91 @@
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/ddcb_info
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    DDCB queue dump used for debugging queueing problems.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/curr_regs
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Dump of the current error registers.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/curr_dbg_uid0
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID0 (unit id 0).
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/curr_dbg_uid1
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID1.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/curr_dbg_uid2
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID2.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/prev_regs
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Dump of the error registers before the last reset of
+                the card occurred.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/prev_dbg_uid0
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID0 before card was reset.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/prev_dbg_uid1
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID1 before card was reset.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/prev_dbg_uid2
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Internal chip state of UID2 before card was reset.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/info
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Comprehensive summary of bitstream version and software
+                version. Used bitstream and bitstream clocking information.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/err_inject
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Possibility to inject error cases to ensure that the drivers
+                error handling code works well.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/vf<0..14>_jobtimeout_msec
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Default VF timeout 250ms. Testing might require 1000ms.
+                Using 0 will use the cards default value (whatever that is).
+
+                The timeout depends on the max number of available cards
+                in the system and the maximum allowed queue size.
+
+                The driver ensures that the settings are done just before
+                the VFs get enabled. Changing the timeouts in flight is not
+                possible.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/jobtimer
+Date:           Oct 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Dump job timeout register values for PF and VFs.
+                Only available for PF.
+
+What:           /sys/kernel/debug/genwqe/genwqe<n>_card/queue_working_time
+Date:           Dec 2013
+Contact:        haver@linux.vnet.ibm.com
+Description:    Dump queue working time register values for PF and VFs.
+                Only available for PF.