ata: fix wrong WARN_ON_ONCE

This patch fixes a wrong WARN_ON that was triggered by 32bit PIO support:
WARNING: at drivers/ata/libata-sff.c:1017 ata_sff_hsm_move+0x45e/0x750()

__atapi_pio_bytes simply doesnt know enough to decide if there is a bug.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 0eae9b453556..5a4aad123c42 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -1013,9 +1013,12 @@ next_sg:
                 qc->cursg_ofs = 0;
         }
 
-        /* consumed can be larger than count only for the last transfer */
-        WARN_ON_ONCE(qc->cursg && count != consumed);
-
+        /*
+         * There used to be a  WARN_ON_ONCE(qc->cursg && count != consumed);
+         * Unfortunately __atapi_pio_bytes doesn't know enough to do the WARN
+         * check correctly as it doesn't know if it is the last request being
+         * made. Somebody should implement a proper sanity check.
+         */
         if (bytes)
                 goto next_sg;
         return 0;