Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata

Pull libata fixes from Tejun Heo:
 "Late libata fixes.

  The most important one is from Kevin Hao which makes sure that libata
  only allocates tags inside the max tag number the controller supports.
  libata always had this problem but the recent tag allocation change
  and addition of support for sata_fsl which only supports queue depth
  of 16 exposed the issue.

  Hans de Goede agreed to become the maintainer of libahci_platform
  which is under higher than usual development pressure from all the new
  controllers popping up from the ARM world"

* 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ahci: add support for the Promise FastTrak TX8660 SATA HBA (ahci mode)
  drivers/ata/pata_ep93xx.c: use signed int type for result of platform_get_irq()
  libata: EH should handle AMNF error condition as a media error
  libata: support the ata host which implements a queue depth less than 32
  MAINTAINERS: Add Hans de Goede as ahci-platform maintainer

1 files changed, 19 insertions, 3 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 18d97d5c7d90..d19c37a7abc9 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4787,6 +4787,10 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
  *	ata_qc_new - Request an available ATA command, for queueing
  *	@ap: target port
  *
+ *	Some ATA host controllers may implement a queue depth which is less
+ *	than ATA_MAX_QUEUE. So we shouldn't allocate a tag which is beyond
+ *	the hardware limitation.
+ *
  *	LOCKING:
  *	None.
  */
@@ -4794,14 +4798,16 @@ 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;
+	unsigned int i, tag, max_queue;
+
+	max_queue = ap->scsi_host->can_queue;
 
 	/* no command while frozen */
 	if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
 		return NULL;
 
-	for (i = 0; i < ATA_MAX_QUEUE; i++) {
-		tag = (i + ap->last_tag + 1) % ATA_MAX_QUEUE;
+	for (i = 0, tag = ap->last_tag + 1; i < max_queue; i++, tag++) {
+		tag = tag < max_queue ? tag : 0;
 
 		/* the last tag is reserved for internal command. */
 		if (tag == ATA_TAG_INTERNAL)
@@ -6169,6 +6175,16 @@ 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");