[PATCH 1/2] libata: Fix scsi_host can_queue issue in ata_qc_new()

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

The can_queue in scsi_host can be more than ATA_MAX_QUEUE (32),
for example, in ipr, it can be 100 or more.

Also, some drivers, like ipr driver, haven't filled the field
scsi_host in ata_port, and will lead a call trace, so add
check for that.

Signed-off-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
---
 drivers/ata/libata-core.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 259d879..a5b9c70 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4734,7 +4734,10 @@ 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;
+	if (ap->scsi_host && ap->scsi_host->can_queue <= ATA_MAX_QUEUE)
+		max_queue = ap->scsi_host->can_queue;
+	else
+		max_queue = ATA_MAX_QUEUE;
 
 	/* no command while frozen */
 	if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
@@ -6109,16 +6112,6 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
 {
 	int i, rc;
 
-	/*
-	 * 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 must have been started */
 	if (!(host->flags & ATA_HOST_STARTED)) {
 		dev_err(host->dev, "BUG: trying to register unstarted host\n");
-- 
1.8.1.4