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, 121 insertions, 0 deletions

diff --git a/fs/coda/cache.c b/fs/coda/cache.c
new file mode 100644
index 000000000..245131296
--- /dev/null
+++ b/fs/coda/cache.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cache operations for Coda.
+ * For Linux 2.1: (C) 1997 Carnegie Mellon University
+ * For Linux 2.3: (C) 2000 Carnegie Mellon University
+ *
+ * Carnegie Mellon encourages users of this code to contribute improvements
+ * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/uaccess.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#include <linux/coda.h>
+#include "coda_psdev.h"
+#include "coda_linux.h"
+#include "coda_cache.h"
+
+static atomic_t permission_epoch = ATOMIC_INIT(0);
+
+/* replace or extend an acl cache hit */
+void coda_cache_enter(struct inode *inode, int mask)
+{
+	struct coda_inode_info *cii = ITOC(inode);
+
+	spin_lock(&cii->c_lock);
+	cii->c_cached_epoch = atomic_read(&permission_epoch);
+	if (!uid_eq(cii->c_uid, current_fsuid())) {
+		cii->c_uid = current_fsuid();
+                cii->c_cached_perm = mask;
+        } else
+                cii->c_cached_perm |= mask;
+	spin_unlock(&cii->c_lock);
+}
+
+/* remove cached acl from an inode */
+void coda_cache_clear_inode(struct inode *inode)
+{
+	struct coda_inode_info *cii = ITOC(inode);
+	spin_lock(&cii->c_lock);
+	cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
+	spin_unlock(&cii->c_lock);
+}
+
+/* remove all acl caches */
+void coda_cache_clear_all(struct super_block *sb)
+{
+	atomic_inc(&permission_epoch);
+}
+
+
+/* check if the mask has been matched against the acl already */
+int coda_cache_check(struct inode *inode, int mask)
+{
+	struct coda_inode_info *cii = ITOC(inode);
+	int hit;
+	
+	spin_lock(&cii->c_lock);
+	hit = (mask & cii->c_cached_perm) == mask &&
+	    uid_eq(cii->c_uid, current_fsuid()) &&
+	    cii->c_cached_epoch == atomic_read(&permission_epoch);
+	spin_unlock(&cii->c_lock);
+
+	return hit;
+}
+
+
+/* Purging dentries and children */
+/* The following routines drop dentries which are not
+   in use and flag dentries which are in use to be 
+   zapped later.
+
+   The flags are detected by:
+   - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
+   - coda_dentry_delete: to remove dentry from the cache when d_count
+     falls to zero
+   - an inode method coda_revalidate (for attributes) if the 
+     flag is C_VATTR
+*/
+
+/* this won't do any harm: just flag all children */
+static void coda_flag_children(struct dentry *parent, int flag)
+{
+	struct dentry *de;
+
+	spin_lock(&parent->d_lock);
+	rcu_read_lock();
+	hlist_for_each_entry(de, &parent->d_children, d_sib) {
+		struct inode *inode = d_inode_rcu(de);
+		/* don't know what to do with negative dentries */
+		if (inode)
+			coda_flag_inode(inode, flag);
+	}
+	rcu_read_unlock();
+	spin_unlock(&parent->d_lock);
+}
+
+void coda_flag_inode_children(struct inode *inode, int flag)
+{
+	struct dentry *alias_de;
+
+	if ( !inode || !S_ISDIR(inode->i_mode)) 
+		return; 
+
+	alias_de = d_find_alias(inode);
+	if (!alias_de)
+		return;
+	coda_flag_children(alias_de, flag);
+	shrink_dcache_parent(alias_de);
+	dput(alias_de);
+}
+