Re: [PATCH 3/3] megaraid_sas: Convert SHT->queuecommand() to run host_lock-less

[Christoph Hellwig <hch@lst.de>]

On Sat, Nov 27, 2010 at 11:17:36PM -0800, Nicholas A. Bellinger wrote:
>  /**
> - * megasas_get_cmd -	Get a command from the free pool
> + * __megasas_get_cmd -	Get a command from the free pool
>   * @instance:		Adapter soft state
>   *
>   * Returns a free command from the pool
> + * Locking: Called with instance->cmd_pool_lock w/ spin_lock_irqsave
>   */
> -static struct megasas_cmd *megasas_get_cmd(struct megasas_instance
> -						  *instance)
> +static struct megasas_cmd *
> +__megasas_get_cmd(struct megasas_instance *instance)
>  {
> +	struct megasas_cmd *cmd;
>  	unsigned long flags;
> -	struct megasas_cmd *cmd = NULL;
>  
>  	spin_lock_irqsave(&instance->cmd_pool_lock, flags);

--- snip ---

> +static struct megasas_cmd *
> +megasas_get_cmd(struct megasas_instance *instance)
> +{
> +	struct megasas_cmd *cmd;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&instance->cmd_pool_lock, flags);

I can't see how this works.