[PATCH 1/1] driver core: Keep the supplier fwnode consistent with the device

[PATCH 1/1] driver core: Keep the supplier fwnode consistent with the device

[Herve Codina]

The commit 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child
fwnode's consumer links") introduces the possibility to use the
supplier's parent device instead of the supplier itself.
In that case the supplier fwnode used is not updated and is no more
consistent with the supplier device used.

Update the fwnode used to be consistent with the supplier device used.

Fixes: 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child fwnode's consumer links")
Cc: stable@vger.kernel.org
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 drivers/base/core.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4d8b315c48a1..17f2568e0a79 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2076,6 +2076,18 @@ static int fw_devlink_create_devlink(struct device *con,
 		sup_dev = get_dev_from_fwnode(sup_handle);
 
 	if (sup_dev) {
+		/*
+		 * The supplier device may have changed and so, the supplier
+		 * fwnode maybe inconsistent.
+		 * Update the supplier fwnode
+		 */
+		sup_handle = sup_dev->fwnode;
+		if (!sup_handle) {
+			dev_dbg(con, "Not linking %s - fwnode NULL\n",
+				dev_name(sup_dev));
+			goto out;
+		}
+
 		/*
 		 * If it's one of those drivers that don't actually bind to
 		 * their device using driver core, then don't wait on this
-- 
2.41.0

Re: [PATCH 1/1] driver core: Keep the supplier fwnode consistent with the device

[Saravana Kannan]

On Thu, Nov 9, 2023 at 11:56 PM Herve Codina <herve.codina@bootlin.com> wrote:
>
> The commit 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child
> fwnode's consumer links") introduces the possibility to use the
> supplier's parent device instead of the supplier itself.
> In that case the supplier fwnode used is not updated and is no more
> consistent with the supplier device used.
>
> Update the fwnode used to be consistent with the supplier device used.
>
> Fixes: 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child fwnode's consumer links")
> Cc: stable@vger.kernel.org
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> ---
>  drivers/base/core.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 4d8b315c48a1..17f2568e0a79 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -2076,6 +2076,18 @@ static int fw_devlink_create_devlink(struct device *con,
>                 sup_dev = get_dev_from_fwnode(sup_handle);
>
>         if (sup_dev) {
> +               /*
> +                * The supplier device may have changed and so, the supplier
> +                * fwnode maybe inconsistent.
> +                * Update the supplier fwnode
> +                */
> +               sup_handle = sup_dev->fwnode;
> +               if (!sup_handle) {
> +                       dev_dbg(con, "Not linking %s - fwnode NULL\n",
> +                               dev_name(sup_dev));
> +                       goto out;
> +               }
> +

Nack. It's easier to debug when you know what supplier you were
pointing to in DT that triggered the creation of the device link. The
parent could be several levels up and multiple supplier links might be
skipped for various reasons. If they all printed the parent's fwnode,
it'll be confusing to debug.

-Saravana

>                 /*
>                  * If it's one of those drivers that don't actually bind to
>                  * their device using driver core, then don't wait on this
> --
> 2.41.0
>

Re: [PATCH 1/1] driver core: Keep the supplier fwnode consistent with the device

[Herve Codina]

Hi Saravana,

On Fri, 10 Nov 2023 17:50:07 -0800
Saravana Kannan <saravanak@google.com> wrote:

> On Thu, Nov 9, 2023 at 11:56 PM Herve Codina <herve.codina@bootlin.com> wrote:
> >
> > The commit 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child
> > fwnode's consumer links") introduces the possibility to use the
> > supplier's parent device instead of the supplier itself.
> > In that case the supplier fwnode used is not updated and is no more
> > consistent with the supplier device used.
> >
> > Update the fwnode used to be consistent with the supplier device used.
> >
> > Fixes: 3a2dbc510c43 ("driver core: fw_devlink: Don't purge child fwnode's consumer links")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> > ---
> >  drivers/base/core.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index 4d8b315c48a1..17f2568e0a79 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -2076,6 +2076,18 @@ static int fw_devlink_create_devlink(struct device *con,
> >                 sup_dev = get_dev_from_fwnode(sup_handle);
> >
> >         if (sup_dev) {
> > +               /*
> > +                * The supplier device may have changed and so, the supplier
> > +                * fwnode maybe inconsistent.
> > +                * Update the supplier fwnode
> > +                */
> > +               sup_handle = sup_dev->fwnode;
> > +               if (!sup_handle) {
> > +                       dev_dbg(con, "Not linking %s - fwnode NULL\n",
> > +                               dev_name(sup_dev));
> > +                       goto out;
> > +               }
> > +  
> 
> Nack. It's easier to debug when you know what supplier you were
> pointing to in DT that triggered the creation of the device link. The
> parent could be several levels up and multiple supplier links might be
> skipped for various reasons. If they all printed the parent's fwnode,
> it'll be confusing to debug.

In fact, I will remove the check if(!sup_handle) in the next iteration.

Indeed, sup_handle cannot be NULL.
sup_dev is retrieved from fwnode_get_next_parent_dev() or get_dev_from_fwnode().
In both cases, if sup_dev is valid, sup_dev->fwnode is valid too.
So, the check and the dev_dbg() call make no sense.

Best regards,
Hervé