[PATCH] arm64: Fix compile error seen in non-SMP builds

[linux@roeck-us.net (Guenter Roeck)]

On Fri, Oct 10, 2014 at 06:15:34PM -0700, Guenter Roeck wrote:
> Fix:
> 
> In file included from ./arch/arm64/include/asm/irq_work.h:4:0,
>         from include/linux/irq_work.h:46,
>         from include/linux/perf_event.h:49,
>         from include/linux/ftrace_event.h:9,
>         from include/trace/syscall.h:6,
>         from include/linux/syscalls.h:81,
>         from init/main.c:18:
> ./arch/arm64/include/asm/smp.h:24:3:
> 	error: #error "<asm/smp.h> included in non-SMP build"
>  # error "<asm/smp.h> included in non-SMP build"
>    ^
> ./arch/arm64/include/asm/smp.h:27:0: warning: "raw_smp_processor_id" redefined
>  #define raw_smp_processor_id() (current_thread_info()->cpu)
>  ^
> 
> and:
> 
> In file included from ./arch/arm64/include/asm/irq_work.h:4:0,
>         from include/linux/irq_work.h:46,
>         from kernel/irq_work.c:11:
> ./arch/arm64/include/asm/smp_plat.h:56:30:
>         error: ?NR_CPUS? undeclared here (not in a function)
>         extern u64 __cpu_logical_map[NR_CPUS];
> 
> by providing a helper function in smp_plat.h, similar to the arm implementation,
> and by removing NR_CPUS from smp_plat.h.
> 
> Fixes: 3631073659d0 ("arm64: Tell irq work about self IPI support")
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

ping ...

The commit causing the problem has been applied to 3.17, meaning
this patch, once in mainline, will have to be applied to 3.17 as well.

Guenter

> ---
> Compile tested and booted in qemu for both SMP and non-SMP builds.
> 
>  arch/arm64/include/asm/irq_work.h |  4 ++--
>  arch/arm64/include/asm/smp.h      |  2 --
>  arch/arm64/include/asm/smp_plat.h | 17 ++++++++++++++++-
>  3 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/irq_work.h b/arch/arm64/include/asm/irq_work.h
> index 8e24ef3..33199a9 100644
> --- a/arch/arm64/include/asm/irq_work.h
> +++ b/arch/arm64/include/asm/irq_work.h
> @@ -1,11 +1,11 @@
>  #ifndef __ASM_IRQ_WORK_H
>  #define __ASM_IRQ_WORK_H
>  
> -#include <asm/smp.h>
> +#include <asm/smp_plat.h>
>  
>  static inline bool arch_irq_work_has_interrupt(void)
>  {
> -	return !!__smp_cross_call;
> +	return have_smp_crosscall();
>  }
>  
>  #endif /* __ASM_IRQ_WORK_H */
> diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
> index 780f82c..a498f2c 100644
> --- a/arch/arm64/include/asm/smp.h
> +++ b/arch/arm64/include/asm/smp.h
> @@ -48,8 +48,6 @@ extern void smp_init_cpus(void);
>   */
>  extern void set_smp_cross_call(void (*)(const struct cpumask *, unsigned int));
>  
> -extern void (*__smp_cross_call)(const struct cpumask *, unsigned int);
> -
>  /*
>   * Called from the secondary holding pen, this is the secondary CPU entry point.
>   */
> diff --git a/arch/arm64/include/asm/smp_plat.h b/arch/arm64/include/asm/smp_plat.h
> index 59e2823..9ae4fde 100644
> --- a/arch/arm64/include/asm/smp_plat.h
> +++ b/arch/arm64/include/asm/smp_plat.h
> @@ -21,6 +21,21 @@
>  
>  #include <asm/types.h>
>  
> +/*
> + * Return true if we are running on a SMP platform
> + * and __smp_cross_call is installed.
> + */
> +static inline bool have_smp_crosscall(void)
> +{
> +#ifndef CONFIG_SMP
> +	return false;
> +#else
> +	extern void (*__smp_cross_call)(const struct cpumask *, unsigned int);
> +
> +	return !!__smp_cross_call;
> +#endif
> +}
> +
>  struct mpidr_hash {
>  	u64	mask;
>  	u32	shift_aff[4];
> @@ -37,7 +52,7 @@ static inline u32 mpidr_hash_size(void)
>  /*
>   * Logical CPU mapping.
>   */
> -extern u64 __cpu_logical_map[NR_CPUS];
> +extern u64 __cpu_logical_map[];
>  #define cpu_logical_map(cpu)    __cpu_logical_map[cpu]
>  
>  #endif /* __ASM_SMP_PLAT_H */
> -- 
> 1.9.1
> 
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