Re: [PATCH v2 3/5] ARM: add IPI tracepoints

[Daniel Lezcano]

On 07/25/2014 10:05 PM, Nicolas Pitre wrote:
> The strings used to list IPIs in /proc/interrupts are reused for tracing
> purposes.
>
> While at it, prevent a negative ipinr from escaping the range check
> in handle_IPI().
>
> Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>

> ---
>   arch/arm/kernel/smp.c | 70 ++++++++++++++++++++++++++++++---------------------
>   1 file changed, 42 insertions(+), 28 deletions(-)
>
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 7c4fada440..9388a3d479 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -47,6 +47,9 @@
>   #include <asm/mach/arch.h>
>   #include <asm/mpu.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/ipi.h>
> +
>   /*
>    * as from 2.5, kernels no longer have an init_tasks structure
>    * so we need some other way of telling a new secondary core
> @@ -430,38 +433,15 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>   	}
>   }
>
> -static void (*smp_cross_call)(const struct cpumask *, unsigned int);
> +static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
>
>   void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
>   {
> -	if (!smp_cross_call)
> -		smp_cross_call = fn;
> -}
> -
> -void arch_send_call_function_ipi_mask(const struct cpumask *mask)
> -{
> -	smp_cross_call(mask, IPI_CALL_FUNC);
> -}
> -
> -void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
> -{
> -	smp_cross_call(mask, IPI_WAKEUP);
> -}
> -
> -void arch_send_call_function_single_ipi(int cpu)
> -{
> -	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
> +	if (!__smp_cross_call)
> +		__smp_cross_call = fn;
>   }
>
> -#ifdef CONFIG_IRQ_WORK
> -void arch_irq_work_raise(void)
> -{
> -	if (is_smp())
> -		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
> -}
> -#endif
> -
> -static const char *ipi_types[NR_IPI] = {
> +static const char *ipi_types[NR_IPI] __tracepoint_string = {
>   #define S(x,s)	[x] = s
>   	S(IPI_WAKEUP, "CPU wakeup interrupts"),
>   	S(IPI_TIMER, "Timer broadcast interrupts"),
> @@ -473,6 +453,12 @@ static const char *ipi_types[NR_IPI] = {
>   	S(IPI_COMPLETION, "completion interrupts"),
>   };
>
> +static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
> +{
> +	trace_ipi_raise(target, ipi_types[ipinr]);
> +	__smp_cross_call(target, ipinr);
> +}
> +
>   void show_ipi_list(struct seq_file *p, int prec)
>   {
>   	unsigned int cpu, i;
> @@ -499,6 +485,29 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
>   	return sum;
>   }
>
> +void arch_send_call_function_ipi_mask(const struct cpumask *mask)
> +{
> +	smp_cross_call(mask, IPI_CALL_FUNC);
> +}
> +
> +void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
> +{
> +	smp_cross_call(mask, IPI_WAKEUP);
> +}
> +
> +void arch_send_call_function_single_ipi(int cpu)
> +{
> +	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
> +}
> +
> +#ifdef CONFIG_IRQ_WORK
> +void arch_irq_work_raise(void)
> +{
> +	if (is_smp())
> +		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
> +}
> +#endif
> +
>   #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
>   void tick_broadcast(const struct cpumask *mask)
>   {
> @@ -556,8 +565,10 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>   	unsigned int cpu = smp_processor_id();
>   	struct pt_regs *old_regs = set_irq_regs(regs);
>
> -	if (ipinr < NR_IPI)
> +	if ((unsigned)ipinr < NR_IPI) {
> +		trace_ipi_entry(ipi_types[ipinr]);
>   		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
> +	}
>
>   	switch (ipinr) {
>   	case IPI_WAKEUP:
> @@ -612,6 +623,9 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>   		       cpu, ipinr);
>   		break;
>   	}
> +
> +	if ((unsigned)ipinr < NR_IPI)
> +		trace_ipi_exit(ipi_types[ipinr]);
>   	set_irq_regs(old_regs);
>   }


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