Re: [PATCH 1/2] powerpc: drop dependency on <asm/machdep.h> in archrandom.h

On Mon, Jul 25, 2022 at 10:22:13PM +1000, Michael Ellerman wrote:

Michael Ellerman [off-list ref] writes:

quoted

Yury Norov [off-list ref] writes:

quoted

archrandom.h includes <asm/machdep.h> to refer ppc_md. This causes
circular header dependency, if generic nodemask.h  includes random.h:

In file included from include/linux/cred.h:16,
                 from include/linux/seq_file.h:13,
                 from arch/powerpc/include/asm/machdep.h:6,
                 from arch/powerpc/include/asm/archrandom.h:5,
                 from include/linux/random.h:109,
                 from include/linux/nodemask.h:97,
                 from include/linux/list_lru.h:12,
                 from include/linux/fs.h:13,
                 from include/linux/compat.h:17,
                 from arch/powerpc/kernel/asm-offsets.c:12:
include/linux/sched.h:1203:9: error: unknown type name 'nodemask_t'
 1203 |         nodemask_t                      mems_allowed;
      |         ^~~~~~~~~~

Fix it by removing <asm/machdep.h> dependency from archrandom.h

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 arch/powerpc/include/asm/archrandom.h |  9 +--------
 arch/powerpc/kernel/setup-common.c    | 11 +++++++++++
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
index 9a53e29680f4..21def59ef1a6 100644
--- a/arch/powerpc/include/asm/archrandom.h
+++ b/arch/powerpc/include/asm/archrandom.h

@@ -4,7 +4,7 @@
 
 #ifdef CONFIG_ARCH_RANDOM
 
-#include <asm/machdep.h>
+bool __must_check arch_get_random_seed_long(unsigned long *v);
 
 static inline bool __must_check arch_get_random_long(unsigned long *v)
 {

@@ -16,13 +16,6 @@ static inline bool __must_check arch_get_random_int(unsigned int *v)
 	return false;
 }
 
-static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
-{
-	if (ppc_md.get_random_seed)
-		return ppc_md.get_random_seed(v);
-
-	return false;
-}

I'd rather we didn't have to force this out of line.

I think I see a different way to fix it, I'll just do some more build
tests.

Of course my idea didn't work :}

So I'll just ack your patch for now, and maybe I can get the headers
cleaned up in future to allow it to be out-of-line again.

I understand that it looks like a tradeoff - we inline a couple of small
functions with the cost of uninlining an almost innocent victim. 

The complete solution would be probably a splitting ppc_md declaration
out of asm/machdep.h. I wanted to do that, but I'm not a PPC guy, and
just don't know how to split the header correctly.

Anyways, thanks for the ack. Applied on bitmap-for-next.

Thanks,
Yury