On 13/12/2021 20.30, Javier Martinez Canillas wrote:
On Mon, Dec 13, 2021 at 11:46 AM Hector Martin <marcan@xxxxxxxxx> wrote:
On 13/12/2021 17.44, Javier Martinez Canillas wrote:
Hello Hector,
On Sun, Dec 12, 2021 at 7:24 AM Hector Martin <marcan@xxxxxxxxx> wrote:
This code is required for both simplefb and simpledrm, so let's move it
into the OF core instead of having it as an ad-hoc initcall in the
drivers.
Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
---
drivers/of/platform.c | 4 ++++
drivers/video/fbdev/simplefb.c | 21 +--------------------
2 files changed, 5 insertions(+), 20 deletions(-)
This is indeed a much better approach than what I suggested. I just
have one comment.
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index b3faf89744aa..793350028906 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -540,6 +540,10 @@ static int __init of_platform_default_populate_init(void)
of_node_put(node);
}
+ node = of_get_compatible_child(of_chosen, "simple-framebuffer");
You have to check if the node variable is NULL here.
+ of_platform_device_create(node, NULL, NULL);
Otherwise this could lead to a NULL pointer dereference if debug
output is enabled (the node->full_name is printed).
Where is it printed? I thought I might need a NULL check, but this code
Sorry, I misread of_amba_device_create() as
of_platform_device_create(), which uses the "%pOF" printk format
specifier [0] to print the node's full name as a debug output [1].
[0]: https://elixir.bootlin.com/linux/v5.16-rc5/source/Documentation/core-api/printk-formats.rst#L462
[1]: https://elixir.bootlin.com/linux/v5.16-rc5/source/drivers/of/platform.c#L233
was suggested verbatim by Rob in v2 without the NULL check and digging
through I found that the NULL codepath is safe.
You are right that passing NULL is a safe code path for now due the
of_device_is_available(node) check, but that seems fragile to me since
just adding a similar debug output to of_platform_device_create()
could trigger the NULL pointer dereference.
Since Rob is the DT maintainer, I'm going to defer to his opinion on
this one :-)
--
Hector Martin (marcan@xxxxxxxxx)
Public Key: https://mrcn.st/pub
