[PATCH] scsi: megaraid_sas: Fix debugfs setup error handling

[PATCH] scsi: megaraid_sas: Fix debugfs setup error handling

[Lei Chen]

debugfs_create_dir() and debugfs_create_file() return error pointers on
failure, but megasas_setup_debugfs() only checks for NULL. As a result,
setup continues after directory creation fails, and a failure to create
raidmap_dump leaves the per-adapter directory behind.

Skip per-adapter setup if the driver debugfs root is unavailable, and
use IS_ERR_OR_NULL() to check directory and file creation results so
that the existing error paths also handle error pointers.

With the corrected error check, file creation failure removes the
per-adapter directory. Clear the stored directory pointer as well so
teardown does not attempt to remove the freed dentry again.

Fixes: ba53572bf02d ("scsi: megaraid_sas: Export RAID map through debugfs")
Signed-off-by: Lei Chen <lei.chen@smartx.com>
---
 drivers/scsi/megaraid/megaraid_sas_debugfs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_debugfs.c b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
index 81698cd83f5a..556e01fc25e8 100644
--- a/drivers/scsi/megaraid/megaraid_sas_debugfs.c
+++ b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
@@ -126,13 +126,16 @@ megasas_setup_debugfs(struct megasas_instance *instance)
 
 	fusion = instance->ctrl_context;
 
+	if (IS_ERR_OR_NULL(megasas_debugfs_root))
+		return;
+
 	if (fusion) {
 		snprintf(name, sizeof(name),
 			 "scsi_host%d", instance->host->host_no);
 		if (!instance->debugfs_root) {
 			instance->debugfs_root =
 				debugfs_create_dir(name, megasas_debugfs_root);
-			if (!instance->debugfs_root) {
+			if (IS_ERR_OR_NULL(instance->debugfs_root)) {
 				dev_err(&instance->pdev->dev,
 					"Cannot create per adapter debugfs directory\n");
 				return;
@@ -144,10 +147,11 @@ megasas_setup_debugfs(struct megasas_instance *instance)
 			debugfs_create_file(name, S_IRUGO,
 					    instance->debugfs_root, instance,
 					    &megasas_debugfs_raidmap_fops);
-		if (!instance->raidmap_dump) {
+		if (IS_ERR_OR_NULL(instance->raidmap_dump)) {
 			dev_err(&instance->pdev->dev,
 				"Cannot create raidmap debugfs file\n");
 			debugfs_remove(instance->debugfs_root);
+			instance->debugfs_root = NULL;
 			return;
 		}
 	}
-- 
2.43.0

Re: [PATCH] scsi: megaraid_sas: Fix debugfs setup error handling

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] scsi: megaraid_sas: debugfs API violation by checking return values and logging errors
--

commit 3a04787b7089e752e49721091a64cf2824d3811c
Author: Lei Chen <lei.chen@smartx.com>

scsi: megaraid_sas: Fix debugfs setup error handling

This commit updates the debugfs setup in megaraid_sas to handle error
pointers by adding IS_ERR_OR_NULL checks. It also ensures that the
per-adapter directory is cleaned up and its pointer cleared if the raidmap
file creation fails.

> diff --git a/drivers/scsi/megaraid/megaraid_sas_debugfs.c b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
> index 81698cd83f5ae..556e01fc25e8e 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_debugfs.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
> @@ -126,13 +126,16 @@ megasas_setup_debugfs(struct megasas_instance *instance)

[ ... ]

>  		if (!instance->debugfs_root) {
>  			instance->debugfs_root =
>  				debugfs_create_dir(name, megasas_debugfs_root);
> -			if (!instance->debugfs_root) {
> +			if (IS_ERR_OR_NULL(instance->debugfs_root)) {
>  				dev_err(&instance->pdev->dev,
>  					"Cannot create per adapter debugfs directory\n");

[Severity: Low]
Does this violate the debugfs API guidelines?

The debugfs guidelines recommend that drivers should not check the return
values of debugfs_create_*() functions.

If debugfs fails, such as due to memory constraints or runtime parameters,
these IS_ERR_OR_NULL() checks in megasas_setup_debugfs() will evaluate to
true and print a dev_err to the kernel log, creating spurious error logs
and adding unnecessary error-handling complexity.

>  				return;
> @@ -144,10 +147,11 @@ megasas_setup_debugfs(struct megasas_instance *instance)
>  			debugfs_create_file(name, S_IRUGO,
>  					    instance->debugfs_root, instance,
>  					    &megasas_debugfs_raidmap_fops);
> -		if (!instance->raidmap_dump) {
> +		if (IS_ERR_OR_NULL(instance->raidmap_dump)) {
>  			dev_err(&instance->pdev->dev,
>  				"Cannot create raidmap debugfs file\n");

[Severity: Low]
Could this be simplified by removing the error check entirely?

Similar to the directory creation above, checking the return value of
debugfs_create_file() here in megasas_setup_debugfs() is generally
discouraged. Removing these checks completely might align better with the
subsystem guidelines.

>  			debugfs_remove(instance->debugfs_root);
> +			instance->debugfs_root = NULL;
>  			return;
>  		}
>  	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007141753.416672-1-lei.chen@smartx.com?part=1

[PATCH v2] scsi: megaraid_sas: Simplify debugfs setup

[Lei Chen]

The debugfs creation helpers return error pointers on failure, so the
existing NULL checks do not handle creation failures. There is no need
to add error handling here: debugfs accepts error pointers as parents
and debugfs_remove_recursive() safely handles error pointers and NULL.

Remove the ineffective checks, error messages and file-creation rollback.
Leave any successfully created directory for the existing teardown path
to remove, even if creating raidmap_dump fails.

The setup function is called only once per instance from probe, so create
the per-adapter directory without checking whether it already exists.

Signed-off-by: Lei Chen <lei.chen@smartx.com>
---
Changes in v2:
- Remove debugfs error checks and logging instead of adding
  IS_ERR_OR_NULL() checks, following review feedback.
- Leave directory cleanup to the existing teardown path.
- Remove the redundant directory existence check, since setup is called
  only once per instance from probe.
- Reframe the patch as a cleanup and drop the Fixes tag.

Link to v1:
https://lore.kernel.org/all/20261007141753.416672-1-lei.chen@smartx.com/

 drivers/scsi/megaraid/megaraid_sas_debugfs.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_debugfs.c b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
index 81698cd83f5a..2fdb4c6bd3d9 100644
--- a/drivers/scsi/megaraid/megaraid_sas_debugfs.c
+++ b/drivers/scsi/megaraid/megaraid_sas_debugfs.c
@@ -102,8 +102,6 @@ static const struct file_operations megasas_debugfs_raidmap_fops = {
 void megasas_init_debugfs(void)
 {
 	megasas_debugfs_root = debugfs_create_dir("megaraid_sas", NULL);
-	if (!megasas_debugfs_root)
-		pr_info("Cannot create debugfs root\n");
 }
 
 /*
@@ -129,27 +127,14 @@ megasas_setup_debugfs(struct megasas_instance *instance)
 	if (fusion) {
 		snprintf(name, sizeof(name),
 			 "scsi_host%d", instance->host->host_no);
-		if (!instance->debugfs_root) {
-			instance->debugfs_root =
-				debugfs_create_dir(name, megasas_debugfs_root);
-			if (!instance->debugfs_root) {
-				dev_err(&instance->pdev->dev,
-					"Cannot create per adapter debugfs directory\n");
-				return;
-			}
-		}
+		instance->debugfs_root =
+			debugfs_create_dir(name, megasas_debugfs_root);
 
 		snprintf(name, sizeof(name), "raidmap_dump");
 		instance->raidmap_dump =
 			debugfs_create_file(name, S_IRUGO,
 					    instance->debugfs_root, instance,
 					    &megasas_debugfs_raidmap_fops);
-		if (!instance->raidmap_dump) {
-			dev_err(&instance->pdev->dev,
-				"Cannot create raidmap debugfs file\n");
-			debugfs_remove(instance->debugfs_root);
-			return;
-		}
 	}
 
 }
-- 
2.43.0