2019-12-07 01:04:02

by Saravana Kannan

Subject: [PATCH v1] of/platform: Unconditionally pause/resume sync state during kernel init

Commit 5e6669387e22 ("of/platform: Pause/resume sync state during init
and of_platform_populate()") paused/resumed sync state during init only
if Linux had parsed and populated a devicetree.

However, the check for that (of_have_populated_dt()) can change between
initcall levels when device tree unittests are enabled. This causes an
unmatched pause/resume of sync state. To avoid this, just
unconditionally pause/resume sync state during init.

Fixes: 5e6669387e22 ("of/platform: Pause/resume sync state during init and of_platform_populate()")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Saravana Kannan <[email protected]>
---
drivers/of/platform.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index d93891a05f60..3371e4a06248 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -518,10 +518,11 @@ static int __init of_platform_default_populate_init(void)
{
struct device_node *node;

+ device_links_supplier_sync_state_pause();
+
if (!of_have_populated_dt())
return -ENODEV;

- device_links_supplier_sync_state_pause();
/*
* Handle certain compatibles explicitly, since we don't want to create
* platform_devices for every node in /reserved-memory with a
@@ -545,8 +546,7 @@ arch_initcall_sync(of_platform_default_populate_init);

static int __init of_platform_sync_state_init(void)
{
- if (of_have_populated_dt())
- device_links_supplier_sync_state_resume();
+ device_links_supplier_sync_state_resume();
return 0;
}
late_initcall_sync(of_platform_sync_state_init);
--
2.24.0.393.g34dc348eaf-goog

2019-12-08 04:53:56

by Frank Rowand

Subject: Re: [PATCH v1] of/platform: Unconditionally pause/resume sync state during kernel init

On 12/6/19 7:03 PM, Saravana Kannan wrote:
> Commit 5e6669387e22 ("of/platform: Pause/resume sync state during init
> and of_platform_populate()") paused/resumed sync state during init only
> if Linux had parsed and populated a devicetree.
>

I _think_ (but I have not actually checked the code) that enabling unittests
is not the only way that of_root can be changed from NULL (thus changing
the value returned by of_have_populated_dt()). I _think_ that applying
an overlay on top of an empty devicetree will have the same result. So
I would change the following paragraph:

> However, the check for that (of_have_populated_dt()) can change between
> initcall levels when device tree unittests are enabled. This causes an
> unmatched pause/resume of sync state. To avoid this, just
> unconditionally pause/resume sync state during init.

to something like:

However, the check for that (of_have_populated_dt()) can change
after of_platform_default_populate_init() executes. One example
of this is when devicetree unittests are enabled. This causes an
nmatched pause/resume of sync state. To avoid this, just
unconditionally pause/resume sync state during init.

>
> Fixes: 5e6669387e22 ("of/platform: Pause/resume sync state during init and of_platform_populate()")
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Saravana Kannan <[email protected]>
> ---
> drivers/of/platform.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index d93891a05f60..3371e4a06248 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -518,10 +518,11 @@ static int __init of_platform_default_populate_init(void)
> {
> struct device_node *node;
>
> + device_links_supplier_sync_state_pause();
> +
> if (!of_have_populated_dt())
> return -ENODEV;
>
> - device_links_supplier_sync_state_pause();
> /*
> * Handle certain compatibles explicitly, since we don't want to create
> * platform_devices for every node in /reserved-memory with a
> @@ -545,8 +546,7 @@ arch_initcall_sync(of_platform_default_populate_init);
>
> static int __init of_platform_sync_state_init(void)
> {
> - if (of_have_populated_dt())
> - device_links_supplier_sync_state_resume();
> + device_links_supplier_sync_state_resume();
> return 0;
> }
> late_initcall_sync(of_platform_sync_state_init);
>

Reviewed-by: Frank Rowand <[email protected]>