[PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[Sasikantha babu]

1) Removed already created debug fs entries on failure

2) Fixed coding style 80 char per line

Signed-off-by: Sasikantha babu <sasikanth.v19@gmail.com>
---
 mm/memblock.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index a44eab3..5553723 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -966,11 +966,19 @@ static int __init memblock_init_debugfs(void)
 {
 	struct dentry *root = debugfs_create_dir("memblock", NULL);
 	if (!root)
-		return -ENXIO;
-	debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
-	debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
+		return -ENOMEM;
+
+	if (!debugfs_create_file("memory", S_IRUGO, root, &memblock.memory,
+				&memblock_debug_fops))
+		goto fail;
+	if (!debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved,
+				&memblock_debug_fops))
+		goto fail;
 
 	return 0;
+fail:
+	debugfs_remove_recursive(root);
+	return -ENOMEM;
 }
 __initcall(memblock_init_debugfs);
 
-- 
1.7.3.4

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Re: [PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[Andrew Morton]

On Thu, 26 Apr 2012 01:29:52 +0530
Sasikantha babu <sasikanth.v19@gmail.com> wrote:

> 1) Removed already created debug fs entries on failure
> 
> 2) Fixed coding style 80 char per line
> 
> Signed-off-by: Sasikantha babu <sasikanth.v19@gmail.com>
> ---
>  mm/memblock.c |   14 +++++++++++---
>  1 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index a44eab3..5553723 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -966,11 +966,19 @@ static int __init memblock_init_debugfs(void)
>  {
>  	struct dentry *root = debugfs_create_dir("memblock", NULL);
>  	if (!root)
> -		return -ENXIO;
> -	debugfs_create_file("memory", S_IRUGO, root, &memblock.memory, &memblock_debug_fops);
> -	debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved, &memblock_debug_fops);
> +		return -ENOMEM;

hm, why the switch to -ENOMEM?

Fact is, debugfs_create_dir() and debugfs_create_file() are stupid
interfaces which don't provide the caller (and hence the user) with any
information about why they failed.  Perhaps memblock_init_debugfs()
should return -EWESUCK.

> +	if (!debugfs_create_file("memory", S_IRUGO, root, &memblock.memory,
> +				&memblock_debug_fops))
> +		goto fail;
> +	if (!debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved,
> +				&memblock_debug_fops))
> +		goto fail;
>  
>  	return 0;
> +fail:
> +	debugfs_remove_recursive(root);
> +	return -ENOMEM;
>  }
>  __initcall(memblock_init_debugfs);

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Re: [PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[Sasikanth babu]

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On Fri, Apr 27, 2012 at 4:51 AM, Andrew Morton <akpm@linux-foundation.org>wrote:

> On Thu, 26 Apr 2012 01:29:52 +0530
> Sasikantha babu <sasikanth.v19@gmail.com> wrote:
>
> > 1) Removed already created debug fs entries on failure
> >
> > 2) Fixed coding style 80 char per line
> >
> > Signed-off-by: Sasikantha babu <sasikanth.v19@gmail.com>
> > ---
> >  mm/memblock.c |   14 +++++++++++---
> >  1 files changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/memblock.c b/mm/memblock.c
> > index a44eab3..5553723 100644
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -966,11 +966,19 @@ static int __init memblock_init_debugfs(void)
> >  {
> >       struct dentry *root = debugfs_create_dir("memblock", NULL);
> >       if (!root)
> > -             return -ENXIO;
> > -     debugfs_create_file("memory", S_IRUGO, root, &memblock.memory,
> &memblock_debug_fops);
> > -     debugfs_create_file("reserved", S_IRUGO, root, &memblock.reserved,
> &memblock_debug_fops);
> > +             return -ENOMEM;
>
> hm, why the switch to -ENOMEM?
>
>     Just for consistency (But its dumb mistake I made).


> Fact is, debugfs_create_dir() and debugfs_create_file() are stupid
> interfaces which don't provide the caller (and hence the user) with any
> information about why they failed.  Perhaps memblock_init_debugfs()
> should return -EWESUCK.
>

   I'm working on a patch which address this issue. debugfs_create_XXX
calls
   will return proper error codes, and fixing the existing code not each
and every part  but the code
   which handles the values returned by debufs_create_XXX otherwise it will
break the existing
   functionality . (any suggestions or opinions ?)
   .

Thanks
Sasi

>
> > +     if (!debugfs_create_file("memory", S_IRUGO, root, &memblock.memory,
> > +                             &memblock_debug_fops))
> > +             goto fail;
> > +     if (!debugfs_create_file("reserved", S_IRUGO, root,
> &memblock.reserved,
> > +                             &memblock_debug_fops))
> > +             goto fail;
> >
> >       return 0;
> > +fail:
> > +     debugfs_remove_recursive(root);
> > +     return -ENOMEM;
> >  }
> >  __initcall(memblock_init_debugfs);
>
>

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Re: [PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[Andrew Morton]

On Sun, 29 Apr 2012 00:32:26 +0530 Sasikanth babu <sasikanth.v19@gmail.com> wrote:

> > Fact is, debugfs_create_dir() and debugfs_create_file() are stupid
> > interfaces which don't provide the caller (and hence the user) with any
> > information about why they failed.  Perhaps memblock_init_debugfs()
> > should return -EWESUCK.
> >
> 
>    I'm working on a patch which address this issue. debugfs_create_XXX
> calls
>    will return proper error codes, and fixing the existing code not each
> and every part  but the code
>    which handles the values returned by debufs_create_XXX otherwise it will
> break the existing
>    functionality .

Excellent!

> (any suggestions or opinions ?)

Well, don't modify the existing interfaces: create new ones and we can
migrate gradually.  But you're probably already doing that.

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Re: [PATCH 2/2] mm: memblock - Handled failure of debug fs entries creation

[Sasikanth babu]

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On Sun, Apr 29, 2012 at 12:36 AM, Andrew Morton
<akpm@linux-foundation.org>wrote:

> On Sun, 29 Apr 2012 00:32:26 +0530 Sasikanth babu <sasikanth.v19@gmail.com>
> wrote:
>
> > > Fact is, debugfs_create_dir() and debugfs_create_file() are stupid
> > > interfaces which don't provide the caller (and hence the user) with any
> > > information about why they failed.  Perhaps memblock_init_debugfs()
> > > should return -EWESUCK.
> > >
> >
> >    I'm working on a patch which address this issue. debugfs_create_XXX
> > calls
> >    will return proper error codes, and fixing the existing code not each
> > and every part  but the code
> >    which handles the values returned by debufs_create_XXX otherwise it
> will
> > break the existing
> >    functionality .
>
> Excellent!
>
> > (any suggestions or opinions ?)
>
> Well, don't modify the existing interfaces: create new ones and we can
> migrate gradually.  But you're probably already doing that.
>

  Not going to change the existing interface.  Modified debugfs_create_XXX
  to return ERR_PTR(error) instead of NULL.

[sasikantha@localhost linux-2.6]$ git diff
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index b80bc84..f5a5783 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -378,7 +378,7 @@ struct dentry *debugfs_create_file(const char *name,
umode_t mode,
        error = debugfs_create_by_name(name, mode, parent, &dentry,
                                       data, fops);
        if (error) {
-               dentry = NULL;
+               dentry = ERR_PTR(error);
                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
                goto exit;
        }

  And from the caller side modifying the code as shown below (Currently
started doing
  modification for each subsystem)

        dir = debugfs_create_dir("test", NULL);

        if (IS_ERR(dir)) {
            return PTR_ERR(dir);
       }

   I think as you had mentioned creating new interface and migrating
gradually is the right of
   way of doing it.

   Thanks
   Sasi

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