Re: [PATCH v3 1/3] gpu/buddy: fix module_init() usage

["Danilo Krummrich" <dakr@kernel.org>]

On Fri Feb 20, 2026 at 7:06 AM CET, Greg KH wrote:
> On Thu, Feb 19, 2026 at 10:38:56PM +0100, Koen Koning wrote:
>> Use subsys_initcall() instead of module_init() (which compiles to
>> device_initcall() for built-ins) for buddy, so its initialization code
>> always runs before any (built-in) drivers.
>> This happened to work correctly so far due to the order of linking in
>> the Makefiles, but this should not be relied upon.
>
> Same here, Makefile order can always be relied on.

I want to point out that Koen's original patch fixed the Makefile order:

diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
index 5cd54d06e262..b4e5e338efa2 100644
--- a/drivers/gpu/Makefile
+++ b/drivers/gpu/Makefile
@@ -2,8 +2,9 @@
 # drm/tegra depends on host1x, so if both drivers are built-in care must be
 # taken to initialize them in the correct order. Link order is the only way
 # to ensure this currently.
+# Similarly, buddy must come first since it is used by other drivers.
+obj-$(CONFIG_GPU_BUDDY)	+= buddy.o
 obj-y			+= host1x/ drm/ vga/ tests/
 obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
 obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
 obj-$(CONFIG_NOVA_CORE)		+= nova-core/
-obj-$(CONFIG_GPU_BUDDY)		+= buddy.o

He was then suggested to not rely on this and rather use subsys_initcall().

When I then came across the new patch using subsys_initcall() I made it worse; I
badly confused this with something else and gave a wrong advise -- sorry Koen!

(Of course, since this is all within the same subsystem, without any external
ordering contraints, Makefile order is sufficient.)