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Re: [PATCH] MIPS: add smp_call_function_single()

To: Stephane Eranian <eranian@hpl.hp.com>
Subject: Re: [PATCH] MIPS: add smp_call_function_single()
From: Ralf Baechle <ralf@linux-mips.org>
Date: Fri, 27 Jul 2007 13:55:33 +0100
Cc: linux-kernel@vger.kernel.org, mucci@cs.utk.edu, linux-mips@linux-mips.org, ak@suse.de, akpm@linux-foundation.org
In-reply-to: <20070727124451.GC9828@frankl.hpl.hp.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070727124451.GC9828@frankl.hpl.hp.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.14 (2007-02-12)
On Fri, Jul 27, 2007 at 05:44:51AM -0700, Stephane Eranian wrote:

> diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
> index be7362b..9e376e2 100644
> --- a/arch/mips/kernel/smp.c
> +++ b/arch/mips/kernel/smp.c
> @@ -193,6 +193,53 @@ void smp_call_function_interrupt(void)
>       }
>  }
>  
> +int smp_call_function_single(int cpu, void (*func) (void *info), void *info, 
> int retry,
> +                          int wait)
> +{
> +  struct call_data_struct data;
> +  int me = smp_processor_id();
> +
> +  /*
> +     * Can die spectacularly if this CPU isn't yet marked online
> +      */
> +  BUG_ON(!cpu_online(me));
> +  if (cpu == me) {
> +    WARN_ON(1);
> +    return -EBUSY;
> +    }
> +
> +  /* Can deadlock when called with interrupts disabled */
> +  WARN_ON(irqs_disabled());
> +
> +  data.func = func;
> +  data.info = info;
> +  atomic_set(&data.started, 0);
> +  data.wait = wait;
> +  if (wait)
> +    atomic_set(&data.finished, 0);
> +
> +  spin_lock(&smp_call_lock);
> +  call_data = &data;
> +  mb();
> +
> +  /* Send a message to the other CPU */
> +  core_send_ipi(cpu, SMP_CALL_FUNCTION);
> +
> +  /* Wait for response */
> +  /* FIXME: lock-up detection, backtrace on lock-up */
> +  while (atomic_read(&data.started) != 1)
> +    barrier();
> +
> +  if (wait)
> +    while (atomic_read(&data.finished) != 1)
> +      barrier();
> +  call_data = NULL;
> +  spin_unlock(&smp_call_lock);
> +
> +  return 0;
> +}
> +EXPORT_SYMBOL(smp_call_function_single);

Please fix the indentation to use tabs as per Documentation/CodingStyle.

>  static void stop_this_cpu(void *dummy)
>  {
>       /*
> diff --git a/include/asm-mips/smp.h b/include/asm-mips/smp.h
> index 13aef6a..5acbf38 100644
> --- a/include/asm-mips/smp.h
> +++ b/include/asm-mips/smp.h
> @@ -102,6 +102,8 @@ static inline void smp_send_reschedule(int cpu)
>       core_send_ipi(cpu, SMP_RESCHEDULE_YOURSELF);
>  }
>  
> +extern int smp_call_function_single(int cpuid, void (*func) (void *info),
> +                             void *info, int retry, int wait);

The function is already declared in include/linux/smp.h so this segment
is unecessary.

  Ralf

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