The debugfs_create_dir() and debugfs_create_file() functions return
ERR_PTR() on error, not NULL. The current null-checks fail to detect
errors because ERR_PTR() encodes error codes as non-null pointer values.

Replace the null-checks with IS_ERR() for all debugfs_create_dir() and
debugfs_create_file() and ras_get_debugfs_root calls to properly
handle errors.

Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector")
Suggested-by: Zhuo, Qiuxu <qiuxu.zhuo@intel.com>
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
Changes in v2:
  -Add fixes in create_debugfs_nodes() and ras_add_daemon_trace()
   as suggested by Zhuo, Qiuxu.
---
 drivers/ras/cec.c     | 12 ++++++------
 drivers/ras/debugfs.c |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index e440b15fbabc..25aa5f2a18b2 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -483,27 +483,27 @@ static int __init create_debugfs_nodes(void)
 	struct dentry *d, *pfn, *decay, *count, *array, *dfs;
 
 	dfs = ras_get_debugfs_root();
-	if (!dfs) {
+	if (IS_ERR(dfs)) {
 		pr_warn("Error getting RAS debugfs root!\n");
 		return -1;
 	}
 
 	d = debugfs_create_dir("cec", dfs);
-	if (!d) {
+	if (IS_ERR(d)) {
 		pr_warn("Error creating cec debugfs node!\n");
 		return -1;
 	}
 
 	decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
 				    &decay_interval, &decay_interval_ops);
-	if (!decay) {
+	if (IS_ERR(decay)) {
 		pr_warn("Error creating decay_interval debugfs node!\n");
 		goto err;
 	}
 
 	count = debugfs_create_file("action_threshold", S_IRUSR | S_IWUSR, d,
 				    &action_threshold, &action_threshold_ops);
-	if (!count) {
+	if (IS_ERR(count)) {
 		pr_warn("Error creating action_threshold debugfs node!\n");
 		goto err;
 	}
@@ -512,13 +512,13 @@ static int __init create_debugfs_nodes(void)
 		return 0;
 
 	pfn = debugfs_create_file("pfn", S_IRUSR | S_IWUSR, d, &dfs_pfn, &pfn_ops);
-	if (!pfn) {
+	if (IS_ERR(pfn)) {
 		pr_warn("Error creating pfn debugfs node!\n");
 		goto err;
 	}
 
 	array = debugfs_create_file("array", S_IRUSR, d, NULL, &array_fops);
-	if (!array) {
+	if (IS_ERR(array)) {
 		pr_warn("Error creating array debugfs node!\n");
 		goto err;
 	}
diff --git a/drivers/ras/debugfs.c b/drivers/ras/debugfs.c
index 42afd3de68b2..8f817bd9cb09 100644
--- a/drivers/ras/debugfs.c
+++ b/drivers/ras/debugfs.c
@@ -47,7 +47,7 @@ int __init ras_add_daemon_trace(void)
 {
 	struct dentry *fentry;
 
-	if (!ras_debugfs_dir)
+	if (IS_ERR(ras_debugfs_dir))
 		return -ENOENT;
 
 	fentry = debugfs_create_file("daemon_active", S_IRUSR, ras_debugfs_dir,
-- 
2.50.1.windows.1

On Thu, Nov 20, 2025 at 04:07:08PM +0800, Haotian Zhang wrote:
> The debugfs_create_dir() and debugfs_create_file() functions return
> ERR_PTR() on error, not NULL. The current null-checks fail to detect
> errors because ERR_PTR() encodes error codes as non-null pointer values.
> 
> Replace the null-checks with IS_ERR() for all debugfs_create_dir() and
> debugfs_create_file() and ras_get_debugfs_root calls to properly
> handle errors.
> 
> Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector")

git show 011d82611172:fs/debugfs/inode.c
...
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
{
        struct dentry *dentry = start_creating(name, parent);
        struct inode *inode;
 
        if (IS_ERR(dentry))
                return NULL;
		^^^^^^^^^^^

So it used to return NULL at the time.

However,

/**     
 * debugfs_create_file - create a file in the debugfs filesystem

	...

 * NOTE: it's expected that most callers should _ignore_ the errors returned
 * by this function. Other debugfs functions handle the fact that the "dentry"
 * passed to them could be an error and they don't crash in that case.
 * Drivers should generally work fine even if debugfs fails to init anyway.
 */

and the _dir() one has the same note. I've been hesitant to remove that error
handling in cec.c until now but I think we can safely zap it. It is
unnecessary clutter by now.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette