arch/i386/kernel/nmi.c: fix compiler warning

arch/i386/kernel/nmi.c: fix compiler warning

[Lee Revell]

arch/i386/kernel/nmi.c: In function 'check_nmi_watchdog':
arch/i386/kernel/nmi.c:139: warning: statement with no effect

Signed-Off-By: Lee Revell <rlrevell@joe-job.com>

--- linux-2.6.16-rc1/arch/i386/kernel/nmi.c~	2006-01-17 02:44:47.000000000 -0500
+++ linux-2.6.16-rc1/arch/i386/kernel/nmi.c	2006-01-26 15:30:59.000000000 -0500
@@ -135,8 +135,10 @@
 
 	printk(KERN_INFO "Testing NMI watchdog ... ");
 
+#ifdef CONFIG_SMP
 	if (nmi_watchdog == NMI_LOCAL_APIC)
 		smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
+#endif
 
 	for (cpu = 0; cpu < NR_CPUS; cpu++)
 		prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count;

Re: arch/i386/kernel/nmi.c: fix compiler warning

[Joe Perches]

On Thu, 2006-01-26 at 15:33 -0500, Lee Revell wrote:
> arch/i386/kernel/nmi.c: In function 'check_nmi_watchdog':
> arch/i386/kernel/nmi.c:139: warning: statement with no effect

A more generic solution:

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 9dfa3ee..be4e598 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -90,12 +90,25 @@ void smp_prepare_boot_cpu(void);
 #else /* !SMP */
 
 /*
- *	These macros fold the SMP functionality into a single CPU system
+ *	These macros and inlines fold the SMP functionality
+ *	for single CPU systems
  */
 #define raw_smp_processor_id()			0
 #define hard_smp_processor_id()			0
-#define smp_call_function(func,info,retry,wait)	({ 0; })
-#define on_each_cpu(func,info,retry,wait)	({ func(info); 0; })
+
+static inline int smp_call_function(void (*func) (void *info), void *info,
+			      int retry, int wait)
+{
+	return 0;
+}
+
+static inline int on_each_cpu(void (*func) (void *info), void *info,
+			      int retry, int wait)
+{
+	func(info);
+	return 0;
+}
+
 static inline void smp_send_reschedule(int cpu) { }
 #define num_booting_cpus()			1
 #define smp_prepare_boot_cpu()			do {} while (0)

Re: arch/i386/kernel/nmi.c: fix compiler warning

[Andrew Morton]

Joe Perches <joe@perches.com> wrote:
>
> --- a/include/linux/smp.h
> +++ b/include/linux/smp.h
> @@ -90,12 +90,25 @@ void smp_prepare_boot_cpu(void);
>  #else /* !SMP */
>  
>  /*
> - *	These macros fold the SMP functionality into a single CPU system
> + *	These macros and inlines fold the SMP functionality
> + *	for single CPU systems
>   */
>  #define raw_smp_processor_id()			0
>  #define hard_smp_processor_id()			0
> -#define smp_call_function(func,info,retry,wait)	({ 0; })
> -#define on_each_cpu(func,info,retry,wait)	({ func(info); 0; })
> +
> +static inline int smp_call_function(void (*func) (void *info), void *info,
> +			      int retry, int wait)
> +{
> +	return 0;
> +}

I think we tried this before and it broke things.  Because there are
callback functions which are inside CONFIG_SMP.  With the macro, they don't
get referred to at all.  Wth the inline, the compiler needs to see their
definition and errors out.