Re: [PATCH 07/11] smp: Consolidate the various smp_call_function_single() declensions

[Jan Kara <jack@suse.cz>]

On Sat 08-02-14 17:18:36, Frederic Weisbecker wrote:
> __smp_call_function_single() and smp_call_function_single() share some
> code that can be factorized: execute inline when the target is local,
> check if the target is online, lock the csd, call generic_exec_single().
> 
> Lets move the common parts to generic_exec_single().
  The patch looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Jens Axboe <jens.axboe@oracle.com>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
>  kernel/smp.c | 80 +++++++++++++++++++++++++++++-------------------------------
>  1 file changed, 39 insertions(+), 41 deletions(-)
> 
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 5ff14e3..64bb0d4 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -117,13 +117,43 @@ static void csd_unlock(struct call_single_data *csd)
>  	csd->flags &= ~CSD_FLAG_LOCK;
>  }
>  
> +static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
> +
>  /*
>   * Insert a previously allocated call_single_data element
>   * for execution on the given CPU. data must already have
>   * ->func, ->info, and ->flags set.
>   */
> -static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
> +static int generic_exec_single(int cpu, struct call_single_data *csd,
> +			       smp_call_func_t func, void *info, int wait)
>  {
> +	struct call_single_data csd_stack = { .flags = 0 };
> +	unsigned long flags;
> +
> +
> +	if (cpu == smp_processor_id()) {
> +		local_irq_save(flags);
> +		func(info);
> +		local_irq_restore(flags);
> +		return 0;
> +	}
> +
> +
> +	if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu))
> +		return -ENXIO;
> +
> +
> +	if (!csd) {
> +		csd = &csd_stack;
> +		if (!wait)
> +			csd = &__get_cpu_var(csd_data);
> +	}
> +
> +	csd_lock(csd);
> +
> +	csd->func = func;
> +	csd->info = info;
> +
>  	if (wait)
>  		csd->flags |= CSD_FLAG_WAIT;
>  
> @@ -143,6 +173,8 @@ static void generic_exec_single(int cpu, struct call_single_data *csd, int wait)
>  
>  	if (wait)
>  		csd_lock_wait(csd);
> +
> +	return 0;
>  }
>  
>  /*
> @@ -168,8 +200,6 @@ void generic_smp_call_function_single_interrupt(void)
>  	}
>  }
>  
> -static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
> -
>  /*
>   * smp_call_function_single - Run a function on a specific CPU
>   * @func: The function to run. This must be fast and non-blocking.
> @@ -181,12 +211,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data);
>  int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
>  			     int wait)
>  {
> -	struct call_single_data d = {
> -		.flags = 0,
> -	};
> -	unsigned long flags;
>  	int this_cpu;
> -	int err = 0;
> +	int err;
>  
>  	/*
>  	 * prevent preemption and reschedule on another processor,
> @@ -203,26 +229,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
>  	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
>  		     && !oops_in_progress);
>  
> -	if (cpu == this_cpu) {
> -		local_irq_save(flags);
> -		func(info);
> -		local_irq_restore(flags);
> -	} else {
> -		if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
> -			struct call_single_data *csd = &d;
> -
> -			if (!wait)
> -				csd = &__get_cpu_var(csd_data);
> -
> -			csd_lock(csd);
> -
> -			csd->func = func;
> -			csd->info = info;
> -			generic_exec_single(cpu, csd, wait);
> -		} else {
> -			err = -ENXIO;	/* CPU not online */
> -		}
> -	}
> +	err = generic_exec_single(cpu, NULL, func, info, wait);
>  
>  	put_cpu();
>  
> @@ -285,9 +292,8 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
>   */
>  int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
>  {
> -	unsigned int this_cpu;
> -	unsigned long flags;
>  	int err = 0;
> +	int this_cpu;
>  
>  	this_cpu = get_cpu();
>  	/*
> @@ -296,20 +302,12 @@ int __smp_call_function_single(int cpu, struct call_single_data *csd, int wait)
>  	 * send smp call function interrupt to this cpu and as such deadlocks
>  	 * can't happen.
>  	 */
> -	WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
> +	WARN_ON_ONCE(cpu_online(this_cpu) && wait && irqs_disabled()
>  		     && !oops_in_progress);
>  
> -	if (cpu == this_cpu) {
> -		local_irq_save(flags);
> -		csd->func(csd->info);
> -		local_irq_restore(flags);
> -	} else if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
> -		csd_lock(csd);
> -		generic_exec_single(cpu, csd, wait);
> -	} else {
> -		err = -ENXIO;	/* CPU not online */
> -	}
> +	err = generic_exec_single(cpu, csd, csd->func, csd->info, wait);
>  	put_cpu();
> +
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(__smp_call_function_single);
> -- 
> 1.8.3.1
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR