* [PATCH] of/platform: increase refcount of fwnode
@ 2023-08-12 12:24 Peng Fan (OSS)
2023-08-15 6:45 ` Andy Shevchenko
2023-08-17 10:57 ` Andy Shevchenko
0 siblings, 2 replies; 7+ messages in thread
From: Peng Fan (OSS) @ 2023-08-12 12:24 UTC (permalink / raw)
To: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
andriy.shevchenko, devicetree, linux-kernel
Cc: Peng Fan
From: Peng Fan <peng.fan@nxp.com>
commit 0f8e5651095b
("of/platform: Propagate firmware node by calling device_set_node()")
use of_fwnode_handle to replace of_node_get, which introduces a side
effect that the refcount is not increased. Then the out of tree
jailhouse hypervisor enable/disable test will trigger kernel dump in
of_overlay_remove, with the following sequence
"
of_changeset_revert(&overlay_changeset);
of_changeset_destroy(&overlay_changeset);
of_overlay_remove(&overlay_id);
"
So increase the refcount to avoid issues.
Fixes: 0f8e5651095b ("of/platform: Propagate firmware node by calling device_set_node()")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
drivers/of/platform.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 0c3475e7d2ff..4659ff5a79c8 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -113,6 +113,7 @@ struct platform_device *of_device_alloc(struct device_node *np,
const char *bus_id,
struct device *parent)
{
+ struct fwnode_handle *fwnode = of_fwnode_handle(np);
struct platform_device *dev;
int rc, i, num_reg = 0;
struct resource *res;
@@ -141,7 +142,7 @@ struct platform_device *of_device_alloc(struct device_node *np,
}
/* setup generic device info */
- device_set_node(&dev->dev, of_fwnode_handle(np));
+ device_set_node(&dev->dev, fwnode_handle_get(fwnode));
dev->dev.parent = parent ? : &platform_bus;
if (bus_id)
@@ -221,6 +222,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
void *platform_data,
struct device *parent)
{
+ struct fwnode_handle *fwnode = of_fwnode_handle(node);
struct amba_device *dev;
int ret;
@@ -239,7 +241,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
/* setup generic device info */
- device_set_node(&dev->dev, of_fwnode_handle(node));
+ device_set_node(&dev->dev, fwnode_handle_get(fwnode));
dev->dev.parent = parent ? : &platform_bus;
dev->dev.platform_data = platform_data;
if (bus_id)
--
2.37.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] of/platform: increase refcount of fwnode
2023-08-12 12:24 [PATCH] of/platform: increase refcount of fwnode Peng Fan (OSS)
@ 2023-08-15 6:45 ` Andy Shevchenko
2023-08-17 1:18 ` Peng Fan
2023-08-17 10:57 ` Andy Shevchenko
1 sibling, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2023-08-15 6:45 UTC (permalink / raw)
To: Peng Fan (OSS)
Cc: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel, Peng Fan
On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> commit 0f8e5651095b
> ("of/platform: Propagate firmware node by calling device_set_node()")
> use of_fwnode_handle to replace of_node_get, which introduces a side
> effect that the refcount is not increased. Then the out of tree
> jailhouse hypervisor enable/disable test will trigger kernel dump in
> of_overlay_remove, with the following sequence
> "
> of_changeset_revert(&overlay_changeset);
> of_changeset_destroy(&overlay_changeset);
> of_overlay_remove(&overlay_id);
> "
>
> So increase the refcount to avoid issues.
Right, thank you for the report!
I was too busy to send myself a fix (I realized about the issue).
But what I think about this the actual platform code has to be balanced with
this. I dunno why we have OF code do one part and the platform core do the
other. It's not obvious and prone to mistakes (like I made).
Let me look to this closer.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH] of/platform: increase refcount of fwnode
2023-08-15 6:45 ` Andy Shevchenko
@ 2023-08-17 1:18 ` Peng Fan
0 siblings, 0 replies; 7+ messages in thread
From: Peng Fan @ 2023-08-17 1:18 UTC (permalink / raw)
To: Andy Shevchenko, Peng Fan (OSS)
Cc: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel
Hi Andy
> Subject: Re: [PATCH] of/platform: increase refcount of fwnode
>
> On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > commit 0f8e5651095b
> > ("of/platform: Propagate firmware node by calling device_set_node()")
> > use of_fwnode_handle to replace of_node_get, which introduces a side
> > effect that the refcount is not increased. Then the out of tree
> > jailhouse hypervisor enable/disable test will trigger kernel dump in
> > of_overlay_remove, with the following sequence "
> > of_changeset_revert(&overlay_changeset);
> > of_changeset_destroy(&overlay_changeset);
> > of_overlay_remove(&overlay_id);
> > "
> >
> > So increase the refcount to avoid issues.
>
> Right, thank you for the report!
> I was too busy to send myself a fix (I realized about the issue).
> But what I think about this the actual platform code has to be balanced with
> this. I dunno why we have OF code do one part and the platform core do
> the other.
No idea, Rob may comment.
It's not obvious and prone to mistakes (like I made).
>
> Let me look to this closer.
It is 6.5-rc6 now, I hope we could land a fix. If you have better fix, that
would be great.
Thanks,
Peng.
>
> --
> With Best Regards,
> Andy Shevchenko
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] of/platform: increase refcount of fwnode
2023-08-12 12:24 [PATCH] of/platform: increase refcount of fwnode Peng Fan (OSS)
2023-08-15 6:45 ` Andy Shevchenko
@ 2023-08-17 10:57 ` Andy Shevchenko
2023-08-17 11:02 ` Andy Shevchenko
1 sibling, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2023-08-17 10:57 UTC (permalink / raw)
To: Peng Fan (OSS)
Cc: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel, Peng Fan
On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> commit 0f8e5651095b
> ("of/platform: Propagate firmware node by calling device_set_node()")
> use of_fwnode_handle to replace of_node_get, which introduces a side
> effect that the refcount is not increased. Then the out of tree
> jailhouse hypervisor enable/disable test will trigger kernel dump in
> of_overlay_remove, with the following sequence
> "
> of_changeset_revert(&overlay_changeset);
> of_changeset_destroy(&overlay_changeset);
> of_overlay_remove(&overlay_id);
> "
>
> So increase the refcount to avoid issues.
I was thinking about this and it's kind quite a tricky thing.
So, let's go with your patch after some modifications, see below.
With that, feel free to add
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
...
> - device_set_node(&dev->dev, of_fwnode_handle(np));
> + device_set_node(&dev->dev, fwnode_handle_get(fwnode));
We know that we only handle OF node here, let's not involve other APIs,
so
device_set_node(&dev->dev, of_fwnode_handle(of_node_get(np)));
...
> - device_set_node(&dev->dev, of_fwnode_handle(node));
> + device_set_node(&dev->dev, fwnode_handle_get(fwnode));
Ditto.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] of/platform: increase refcount of fwnode
2023-08-17 10:57 ` Andy Shevchenko
@ 2023-08-17 11:02 ` Andy Shevchenko
2023-08-17 13:13 ` Peng Fan
0 siblings, 1 reply; 7+ messages in thread
From: Andy Shevchenko @ 2023-08-17 11:02 UTC (permalink / raw)
To: Peng Fan (OSS)
Cc: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel, Peng Fan
On Thu, Aug 17, 2023 at 01:57:39PM +0300, Andy Shevchenko wrote:
> On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
...
> > - device_set_node(&dev->dev, of_fwnode_handle(node));
> > + device_set_node(&dev->dev, fwnode_handle_get(fwnode));
>
> Ditto.
Actually no, amba_device_alloc() does not use platform_device_alloc() and
defines it's own .release method. There is no reference count drop there
AFAICS.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
* RE: [PATCH] of/platform: increase refcount of fwnode
2023-08-17 11:02 ` Andy Shevchenko
@ 2023-08-17 13:13 ` Peng Fan
2023-08-17 14:06 ` Andy Shevchenko
0 siblings, 1 reply; 7+ messages in thread
From: Peng Fan @ 2023-08-17 13:13 UTC (permalink / raw)
To: Andy Shevchenko, Peng Fan (OSS)
Cc: robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel
> Subject: Re: [PATCH] of/platform: increase refcount of fwnode
>
> On Thu, Aug 17, 2023 at 01:57:39PM +0300, Andy Shevchenko wrote:
> > On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
>
> ...
>
> > > - device_set_node(&dev->dev, of_fwnode_handle(node));
> > > + device_set_node(&dev->dev, fwnode_handle_get(fwnode));
> >
> > Ditto.
>
> Actually no, amba_device_alloc() does not use platform_device_alloc() and
> defines it's own .release method. There is no reference count drop there
> AFAICS.
My test only covers platform device, so ..
But I have a general question here. Since of_amba_device_create will use
the of_node or fwnode, shouldn't the refcount_t be increased and released
in amba device release?
Thanks,
Peng.
>
> --
> With Best Regards,
> Andy Shevchenko
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] of/platform: increase refcount of fwnode
2023-08-17 13:13 ` Peng Fan
@ 2023-08-17 14:06 ` Andy Shevchenko
0 siblings, 0 replies; 7+ messages in thread
From: Andy Shevchenko @ 2023-08-17 14:06 UTC (permalink / raw)
To: Peng Fan
Cc: Peng Fan (OSS),
robh+dt, krzysztof.kozlowski+dt, conor+dt, frowand.list,
devicetree, linux-kernel
On Thu, Aug 17, 2023 at 01:13:01PM +0000, Peng Fan wrote:
> > On Thu, Aug 17, 2023 at 01:57:39PM +0300, Andy Shevchenko wrote:
> > > On Sat, Aug 12, 2023 at 08:24:11PM +0800, Peng Fan (OSS) wrote:
...
> > > > - device_set_node(&dev->dev, of_fwnode_handle(node));
> > > > + device_set_node(&dev->dev, fwnode_handle_get(fwnode));
> > >
> > > Ditto.
> >
> > Actually no, amba_device_alloc() does not use platform_device_alloc() and
> > defines it's own .release method. There is no reference count drop there
> > AFAICS.
>
> My test only covers platform device, so ..
>
> But I have a general question here. Since of_amba_device_create will use
> the of_node or fwnode, shouldn't the refcount_t be increased and released
> in amba device release?
I believe so.
Basically we need two changes:
1) this one with the suggested modifications, and
2) fix the reference count leak in amba release.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 7+ messages in thread
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2023-08-12 12:24 [PATCH] of/platform: increase refcount of fwnode Peng Fan (OSS)
2023-08-15 6:45 ` Andy Shevchenko
2023-08-17 1:18 ` Peng Fan
2023-08-17 10:57 ` Andy Shevchenko
2023-08-17 11:02 ` Andy Shevchenko
2023-08-17 13:13 ` Peng Fan
2023-08-17 14:06 ` Andy Shevchenko
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