[PATCH] omap-iommu: no need to check return value of debugfs_create functions

[PATCH] omap-iommu: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Cc: Joerg Roedel <joro@8bytes.org>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Warning, not even test-built, but "should" work :)

 drivers/iommu/omap-iommu-debug.c | 35 ++++++--------------------------
 1 file changed, 6 insertions(+), 29 deletions(-)

diff --git a/drivers/iommu/omap-iommu-debug.c b/drivers/iommu/omap-iommu-debug.c
index 4abc0ef522a8..cea851702f54 100644
--- a/drivers/iommu/omap-iommu-debug.c
+++ b/drivers/iommu/omap-iommu-debug.c
@@ -239,17 +239,6 @@ DEBUG_FOPS_RO(regs);
 DEFINE_SHOW_ATTRIBUTE(tlb);
 DEFINE_SHOW_ATTRIBUTE(pagetable);
 
-#define __DEBUG_ADD_FILE(attr, mode)					\
-	{								\
-		struct dentry *dent;					\
-		dent = debugfs_create_file(#attr, mode, obj->debug_dir,	\
-					   obj, &attr##_fops);	        \
-		if (!dent)						\
-			goto err;					\
-	}
-
-#define DEBUG_ADD_FILE_RO(name) __DEBUG_ADD_FILE(name, 0400)
-
 void omap_iommu_debugfs_add(struct omap_iommu *obj)
 {
 	struct dentry *d;
@@ -257,23 +246,13 @@ void omap_iommu_debugfs_add(struct omap_iommu *obj)
 	if (!iommu_debug_root)
 		return;
 
-	obj->debug_dir = debugfs_create_dir(obj->name, iommu_debug_root);
-	if (!obj->debug_dir)
-		return;
+	d = debugfs_create_dir(obj->name, iommu_debug_root);
+	obj->debug_dir = d;
 
-	d = debugfs_create_u32("nr_tlb_entries", 0400, obj->debug_dir,
-			       &obj->nr_tlb_entries);
-	if (!d)
-		return;
-
-	DEBUG_ADD_FILE_RO(regs);
-	DEBUG_ADD_FILE_RO(tlb);
-	DEBUG_ADD_FILE_RO(pagetable);
-
-	return;
-
-err:
-	debugfs_remove_recursive(obj->debug_dir);
+	debugfs_create_u32("nr_tlb_entries", 0400, d, &obj->nr_tlb_entries);
+	debugfs_create_file("regs", 0400, d, obj, &attrregs_fops);
+	debugfs_create_file("tlb", 0400, d, obj, &attrtlb_fops);
+	debugfs_create_file("pagetable", 0400, d, obj, &attrpagetable_fops);
 }
 
 void omap_iommu_debugfs_remove(struct omap_iommu *obj)
@@ -287,8 +266,6 @@ void omap_iommu_debugfs_remove(struct omap_iommu *obj)
 void __init omap_iommu_debugfs_init(void)
 {
 	iommu_debug_root = debugfs_create_dir("omap_iommu", NULL);
-	if (!iommu_debug_root)
-		pr_err("can't create debugfs dir\n");
 }
 
 void __exit omap_iommu_debugfs_exit(void)
-- 
2.22.0

Re: [PATCH] omap-iommu: no need to check return value of debugfs_create functions

[Joerg Roedel]

On Thu, Jul 04, 2019 at 04:36:49PM +0200, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.
> 
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: iommu@lists.linux-foundation.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> Warning, not even test-built, but "should" work :)

It almost did :)

> +	debugfs_create_file("regs", 0400, d, obj, &attrregs_fops);
> +	debugfs_create_file("tlb", 0400, d, obj, &attrtlb_fops);
> +	debugfs_create_file("pagetable", 0400, d, obj, &attrpagetable_fops);

The _fops were named without the 'attr' prefix, changed that and it
compiled. Patch is now applied.

Thanks,

	Joerg

Re: [PATCH] omap-iommu: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Thu, Jul 04, 2019 at 05:35:52PM +0200, Joerg Roedel wrote:
> On Thu, Jul 04, 2019 at 04:36:49PM +0200, Greg Kroah-Hartman wrote:
> > When calling debugfs functions, there is no need to ever check the
> > return value.  The function can work or not, but the code logic should
> > never do something different based on this.
> > 
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: iommu@lists.linux-foundation.org
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> > Warning, not even test-built, but "should" work :)
> 
> It almost did :)
> 
> > +	debugfs_create_file("regs", 0400, d, obj, &attrregs_fops);
> > +	debugfs_create_file("tlb", 0400, d, obj, &attrtlb_fops);
> > +	debugfs_create_file("pagetable", 0400, d, obj, &attrpagetable_fops);
> 
> The _fops were named without the 'attr' prefix, changed that and it
> compiled. Patch is now applied.

Ah, so close :)

Thanks for fixing it up and applying it!

greg k-h