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, 146 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rtrs-client b/Documentation/ABI/testing/sysfs-class-rtrs-client
new file mode 100644
index 000000000..fecc59d1b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-rtrs-client
@@ -0,0 +1,146 @@
+What:		/sys/class/rtrs-client
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	When a user of RTRS API creates a new session, a directory entry with
+		the name of that session is created under /sys/class/rtrs-client/<session-name>/
+
+What:		/sys/class/rtrs-client/<session-name>/add_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, adds a new path (connection) to an existing session. Expected format is the
+		following::
+
+		    <[source addr,]destination addr>
+		    *addr ::= [ ip:<ipv4|ipv6> | gid:<gid> ]
+
+What:		/sys/class/rtrs-client/<session-name>/max_reconnect_attempts
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Maximum number reconnect attempts the client should make before giving up
+		after connection breaks unexpectedly.
+
+What:		/sys/class/rtrs-client/<session-name>/mp_policy
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Multipath policy specifies which path should be selected on each IO:
+
+		round-robin (0):
+		    select path in per CPU round-robin manner.
+
+		min-inflight (1):
+		    select path with minimum inflights.
+
+		min-latency (2):
+		    select path with minimum latency.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Each path belonging to a given session is listed here by its source and
+		destination address. When a new path is added to a session by writing to
+		the "add_path" entry, a directory <src@dst> is created.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/state
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains "connected" if the session is connected to the peer and fully
+		functional.  Otherwise the file contains "disconnected"
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/reconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to reconnect the path.
+		Operation is blocking and returns 0 if reconnect was successful.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/disconnect
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnect the path.
+		Operation blocks until RTRS path is disconnected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/remove_path
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Write "1" to the file in order to disconnected and remove the path
+		from the session.  Operation blocks until the path is disconnected
+		and removed from the session.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_name
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the name of HCA the connection established on.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/hca_port
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the port number of active port traffic is going through.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/src_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the source address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/dst_addr
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the destination address of the path
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/cur_latency
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RO, Contains the latency time calculated by the heart-beat messages.
+		Whenever the client sends heart-beat message, it checks the time gap
+		between sending the heart-beat message and receiving the ACK.
+		This value can be changed regularly.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reset_all
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RW, Read will return usage help, write 0 will clear all the statistics.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/cpu_migration
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	RTRS expects that each HCA IRQ is pinned to a separate CPU. If it's
+		not the case, the processing of an I/O response could be processed on a
+		different CPU than where it was originally submitted.  This file shows
+		how many interrupts where generated on a non expected CPU.
+
+		"from:"
+		    is the CPU on which the IRQ was expected, but not generated.
+		"to:"
+		    is the CPU on which the IRQ was generated, but not expected.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/reconnects
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains 2 unsigned int values, the first one records number of successful
+		reconnects in the path lifetime, the second one records number of failed
+		reconnects in the path lifetime.
+
+What:		/sys/class/rtrs-client/<session-name>/paths/<src@dst>/stats/rdma
+Date:		Feb 2020
+KernelVersion:	5.7
+Contact:	Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
+Description:	Contains statistics regarding rdma operations and inflight operations.
+		The output consists of 6 values::
+
+		    <read-count> <read-total-size> <write-count> \
+		    <write-total-size> <inflights> <failovered>