Re: [PATCH 2/2] libata: Fix NULL pointer of scsi_host in ata_port

[Mike Qiu <qiudayu@linux.vnet.ibm.com>]

I have tested with the ipr IOA, passed.

Reviewed-and Tested-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>

On 07/23/2014 04:11 AM, Tejun Heo wrote:
> Hello,
>
> Can you please test the following patch?
>
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index d19c37a7..773f4e6 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -4798,9 +4798,8 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
>   static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
>   {
>   	struct ata_queued_cmd *qc = NULL;
> -	unsigned int i, tag, max_queue;
> -
> -	max_queue = ap->scsi_host->can_queue;
> +	unsigned int max_queue = ap->host->n_tags;
> +	unsigned int i, tag;
>
>   	/* no command while frozen */
>   	if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
> @@ -6094,6 +6093,7 @@ void ata_host_init(struct ata_host *host, struct device *dev,
>   {
>   	spin_lock_init(&host->lock);
>   	mutex_init(&host->eh_mutex);
> +	host->n_tags = ATA_MAX_QUEUE;
>   	host->dev = dev;
>   	host->ops = ops;
>   }
> @@ -6179,11 +6179,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
>   	 * The max queue supported by hardware must not be greater than
>   	 * ATA_MAX_QUEUE.
>   	 */
> -	if (sht->can_queue > ATA_MAX_QUEUE) {
> -		dev_err(host->dev, "BUG: the hardware max queue is too large\n");
> -		WARN_ON(1);
> -		return -EINVAL;
> -	}
> +	host->n_tags = clamp(sht->can_queue, 1, ATA_MAX_QUEUE);
>
>   	/* host must have been started */
>   	if (!(host->flags & ATA_HOST_STARTED)) {
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index 5ab4e3a..92abb49 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -593,6 +593,7 @@ struct ata_host {
>   	struct device 		*dev;
>   	void __iomem * const	*iomap;
>   	unsigned int		n_ports;
> +	unsigned int		n_tags;			/* nr of NCQ tags */
>   	void			*private_data;
>   	struct ata_port_operations *ops;
>   	unsigned long		flags;
>