[RFC PATCH powerpc] Fix compiling error in powernv/rng.c

[RFC PATCH powerpc] Fix compiling error in powernv/rng.c

[Li Zhong]

This is seen when CONFIG_SMP is not enabled:

arch/powerpc/platforms/powernv/rng.c: In function 'rng_init_per_cpu':
arch/powerpc/platforms/powernv/rng.c:74: error: implicit declaration of function 'cpu_to_chip_id'

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/rng.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 8844628..04430a7 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -59,6 +59,7 @@ int powernv_get_random_long(unsigned long *v)
 }
 EXPORT_SYMBOL_GPL(powernv_get_random_long);
 
+#ifdef CONFIG_SMP
 static __init void rng_init_per_cpu(struct powernv_rng *rng,
 				    struct device_node *dn)
 {
@@ -75,6 +76,13 @@ static __init void rng_init_per_cpu(struct powernv_rng *rng,
 		}
 	}
 }
+#else
+static __init void rng_init_per_cpu(struct powernv_rng *rng,
+				    struct device_node *dn)
+{
+	per_cpu(powernv_rng, 0) = rng;
+}
+#endif
 
 static __init int rng_create(struct device_node *dn)
 {

Re: [RFC PATCH powerpc] Fix compiling error in powernv/rng.c

[Michael Ellerman]

On Fri, Nov 15, 2013 at 03:36:04PM +0800, Li Zhong wrote:
> This is seen when CONFIG_SMP is not enabled:
> 
> arch/powerpc/platforms/powernv/rng.c: In function 'rng_init_per_cpu':
> arch/powerpc/platforms/powernv/rng.c:74: error: implicit declaration of function 'cpu_to_chip_id'

Hi Li,

We try whenever possible to avoid adding #ifdefs in C code.

Also on a multi chip system where there are multiple RNGs, your code for
UP will not necessarily choose the RNG on the same core as the cpu.

I have a different fix that I will send.

cheers

Re: [RFC PATCH powerpc] Fix compiling error in powernv/rng.c

[Li Zhong]

On Tue, 2013-11-19 at 15:04 +1100, Michael Ellerman wrote:
> On Fri, Nov 15, 2013 at 03:36:04PM +0800, Li Zhong wrote:
> > This is seen when CONFIG_SMP is not enabled:
> > 
> > arch/powerpc/platforms/powernv/rng.c: In function 'rng_init_per_cpu':
> > arch/powerpc/platforms/powernv/rng.c:74: error: implicit declaration of function 'cpu_to_chip_id'
> 
> Hi Li,
> 
> We try whenever possible to avoid adding #ifdefs in C code.
> 
> Also on a multi chip system where there are multiple RNGs, your code for
> UP will not necessarily choose the RNG on the same core as the cpu.

OK, thank you for the review, Michael.

Just try to make sure I understand it: 

So even in UP, we could have multiple rng sources, and we should try to
use the source which has the same chip_id as the logical cpu?

Thanks, Zhong

> I have a different fix that I will send.
> 
> cheers
>