[PATCH net] pds_core: fix debugfs_lookup dentry leak and error handling

["Nikhil P. Rao" <nikhil.rao@amd.com>]

debugfs_lookup() returns a dentry with an elevated reference count that
must be released with dput(). The current code discards the returned
dentry without calling dput(), causing a reference leak on every
firmware reset recovery.

Additionally, when CONFIG_DEBUG_FS is disabled, debugfs_lookup()
returns ERR_PTR(-ENODEV), not NULL. The current check passes for error
pointers and would call dput() on an invalid pointer, causing a crash.

Fixes: bc90fbe0c318 ("pds_core: Rework teardown/setup flow to be more common")
Signed-off-by: Nikhil P. Rao <nikhil.rao@amd.com>
---
 drivers/net/ethernet/amd/pds_core/debugfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/amd/pds_core/debugfs.c b/drivers/net/ethernet/amd/pds_core/debugfs.c
index 04c5e3abd8d7..810a0cd9bcac 100644
--- a/drivers/net/ethernet/amd/pds_core/debugfs.c
+++ b/drivers/net/ethernet/amd/pds_core/debugfs.c
@@ -64,9 +64,14 @@ DEFINE_SHOW_ATTRIBUTE(identity);
 
 void pdsc_debugfs_add_ident(struct pdsc *pdsc)
 {
+	struct dentry *dentry;
+
 	/* This file will already exist in the reset flow */
-	if (debugfs_lookup("identity", pdsc->dentry))
+	dentry = debugfs_lookup("identity", pdsc->dentry);
+	if (!IS_ERR_OR_NULL(dentry)) {
+		dput(dentry);
 		return;
+	}
 
 	debugfs_create_file("identity", 0400, pdsc->dentry,
 			    pdsc, &identity_fops);
-- 
2.43.0