[PATCH] libata: fix WARN_ON() condition in *_fill_sg()

For ATAPI commands, padding can reduce qc->n_elem by one and thus to
zero making assert(qc->n_elem > 0)'s in ata_fill_sg() and qs_fill_sg()
fail for legal commands.  This patch fixes the assert()'s to take
qc->pad_len into account.

Although the condition check seems a bit excessive, as this part of
code isn't still stable yet, I think it's worth to keep those.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 7ddd5a69352a..bbac87a13d57 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2570,7 +2570,7 @@ static void ata_fill_sg(struct ata_queued_cmd *qc)
         unsigned int idx;
 
         assert(qc->__sg != NULL);
-        assert(qc->n_elem > 0);
+        assert(qc->n_elem > 0 || qc->pad_len > 0);
 
         idx = 0;
         ata_for_each_sg(sg, qc) {
diff --git a/drivers/scsi/sata_qstor.c b/drivers/scsi/sata_qstor.c
index de05e2883f9c..80480f0fb2b8 100644
--- a/drivers/scsi/sata_qstor.c
+++ b/drivers/scsi/sata_qstor.c
@@ -277,7 +277,7 @@ static unsigned int qs_fill_sg(struct ata_queued_cmd *qc)
         u8 *prd = pp->pkt + QS_CPB_BYTES;
 
         assert(qc->__sg != NULL);
-        assert(qc->n_elem > 0);
+        assert(qc->n_elem > 0 || qc->pad_len > 0);
 
         nelem = 0;
         ata_for_each_sg(sg, qc) {