[PATCH 02/15] libata: zero xfer length on ATAPI data xfer IRQ is HSM violation

[Tejun Heo <htejun@gmail.com>]

From: Albert Lee <albertcc@tw.ibm.com>

Treat zero xfer length as HSM violation.  While at it, add
unlikely()'s to ATAPI ireason and transfer length checks.

tj: Formatted patch and added unlikely()'s.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
---
 drivers/ata/libata-core.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 597e07c..88f7637 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5280,12 +5280,15 @@ static void atapi_pio_bytes(struct ata_queued_cmd *qc)
 	bytes = (bc_hi << 8) | bc_lo;
 
 	/* shall be cleared to zero, indicating xfer of data */
-	if (ireason & (1 << 0))
+	if (unlikely(ireason & (1 << 0)))
 		goto err_out;
 
 	/* make sure transfer direction matches expected */
 	i_write = ((ireason & (1 << 1)) == 0) ? 1 : 0;
-	if (do_write != i_write)
+	if (unlikely(do_write != i_write))
+		goto err_out;
+
+	if (unlikely(!bytes))
 		goto err_out;
 
 	VPRINTK("ata%u: xfering %d bytes\n", ap->print_id, bytes);
-- 
1.5.2.4