[PATCH v2] dax: fix dax_core_init error return code

[PATCH v2] dax: fix dax_core_init error return code

[jianyungao89]

From: Jianyun Gao <jianyungao89@gmail.com>

dax_core_init() mistakenly returns 0 on error paths. Change the
error return to use rc so the actual error code is propagated
to the caller.

Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
Cc: stable@vger.kernel.org
Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
---

Changes in v2:
- Drop unnecessary goto label, keep direct return for dax_fs_init() error
- Add Fixes tag and Cc stable

Link: https://lore.kernel.org/lkml/20261011132017.31131-1-jianyungao89@gmail.com/ # v1

 drivers/dax/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 45f84b0eb909..210f4af479f0 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -738,7 +738,7 @@ static int __init dax_core_init(void)
 	unregister_chrdev_region(dax_devt, MINORMASK+1);
 err_chrdev:
 	dax_fs_exit();
-	return 0;
+	return rc;
 }
 
 static void __exit dax_core_exit(void)
-- 
2.34.1

Re: [PATCH v2] dax: fix dax_core_init error return code

[Gregory Price]

On Mon, Oct 12, 2026 at 11:18:57PM +0800, jianyungao89@gmail.com wrote:
> From: Jianyun Gao <jianyungao89@gmail.com>
> 
> dax_core_init() mistakenly returns 0 on error paths. Change the
> error return to use rc so the actual error code is propagated
> to the caller.
> 
> Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>

Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>

Re: [PATCH v2] dax: fix dax_core_init error return code

[Alison Schofield]

On Mon, Oct 12, 2026 at 11:18:57PM +0800, jianyungao89@gmail.com wrote:
> From: Jianyun Gao <jianyungao89@gmail.com>
> 
> dax_core_init() mistakenly returns 0 on error paths. Change the
> error return to use rc so the actual error code is propagated
> to the caller.


Hi Jianyun,

Thanks for the patch. The change looks good to me.

I'd like to expand the commit message to explain the impact of the bug,
not just describe the correction. I've proposed a revised message below.

	dax: Return errors from dax_core_init()

	dax_core_init() returns success when either the character device
	number allocation or DAX bus registration fails, even though the
	error paths have already released the initialized resources.

	For modular DAX, this allows the module to remain loaded despite
	failed initialization, leaving subsequent users and module removal
	to access resources that have already been released.

	Return the error code from the failed operation so that module
	loading fails rather than reporting successful initialization
	after the resources have been released.

Please let me know if you're OK with the above, and I'll amend the commit
message and merge the patch.

-- Alison


> 
> Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
> ---
> 
> Changes in v2:
> - Drop unnecessary goto label, keep direct return for dax_fs_init() error
> - Add Fixes tag and Cc stable
> 
> Link: https://lore.kernel.org/lkml/20261011132017.31131-1-jianyungao89@gmail.com/ # v1
> 
>  drivers/dax/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 45f84b0eb909..210f4af479f0 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -738,7 +738,7 @@ static int __init dax_core_init(void)
>  	unregister_chrdev_region(dax_devt, MINORMASK+1);
>  err_chrdev:
>  	dax_fs_exit();
> -	return 0;
> +	return rc;
>  }
>  
>  static void __exit dax_core_exit(void)
> -- 
> 2.34.1
> 

Re: [PATCH v2] dax: fix dax_core_init error return code

[Jianyun Gao]

Hi Dan,

Thank you for reviewing the patch! The revised commit message looks
great to me. I'm OK with it.

Best regards,
Jianyun

On Tue, Oct 13, 2026 at 7:05 AM Alison Schofield
<alison.schofield@intel.com> wrote:
>
> On Mon, Oct 12, 2026 at 11:18:57PM +0800, jianyungao89@gmail.com wrote:
> > From: Jianyun Gao <jianyungao89@gmail.com>
> >
> > dax_core_init() mistakenly returns 0 on error paths. Change the
> > error return to use rc so the actual error code is propagated
> > to the caller.
>
>
> Hi Jianyun,
>
> Thanks for the patch. The change looks good to me.
>
> I'd like to expand the commit message to explain the impact of the bug,
> not just describe the correction. I've proposed a revised message below.
>
>         dax: Return errors from dax_core_init()
>
>         dax_core_init() returns success when either the character device
>         number allocation or DAX bus registration fails, even though the
>         error paths have already released the initialized resources.
>
>         For modular DAX, this allows the module to remain loaded despite
>         failed initialization, leaving subsequent users and module removal
>         to access resources that have already been released.
>
>         Return the error code from the failed operation so that module
>         loading fails rather than reporting successful initialization
>         after the resources have been released.
>
> Please let me know if you're OK with the above, and I'll amend the commit
> message and merge the patch.
>
> -- Alison
>
>
> >
> > Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
> > ---
> >
> > Changes in v2:
> > - Drop unnecessary goto label, keep direct return for dax_fs_init() error
> > - Add Fixes tag and Cc stable
> >
> > Link: https://lore.kernel.org/lkml/20261011132017.31131-1-jianyungao89@gmail.com/ # v1
> >
> >  drivers/dax/super.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> > index 45f84b0eb909..210f4af479f0 100644
> > --- a/drivers/dax/super.c
> > +++ b/drivers/dax/super.c
> > @@ -738,7 +738,7 @@ static int __init dax_core_init(void)
> >       unregister_chrdev_region(dax_devt, MINORMASK+1);
> >  err_chrdev:
> >       dax_fs_exit();
> > -     return 0;
> > +     return rc;
> >  }
> >
> >  static void __exit dax_core_exit(void)
> > --
> > 2.34.1
> >

Re: [PATCH v2] dax: fix dax_core_init error return code

[Dave Jiang]

On 10/12/26 8:18 AM, jianyungao89@gmail.com wrote:
> From: Jianyun Gao <jianyungao89@gmail.com>
> 
> dax_core_init() mistakenly returns 0 on error paths. Change the
> error return to use rc so the actual error code is propagated
> to the caller.
> 
> Fixes: 9567da0b408a ("device-dax: Introduce bus + driver model")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
> 
> Changes in v2:
> - Drop unnecessary goto label, keep direct return for dax_fs_init() error
> - Add Fixes tag and Cc stable
> 
> Link: https://lore.kernel.org/lkml/20261011132017.31131-1-jianyungao89@gmail.com/ # v1
> 
>  drivers/dax/super.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 45f84b0eb909..210f4af479f0 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -738,7 +738,7 @@ static int __init dax_core_init(void)
>  	unregister_chrdev_region(dax_devt, MINORMASK+1);
>  err_chrdev:
>  	dax_fs_exit();
> -	return 0;
> +	return rc;
>  }
>  
>  static void __exit dax_core_exit(void)