libata: fix boot panic with SATAPI devices on non-SFF HBAs

The kernel now panics reliably on boot if you have a SATAPI device
connected.

The problem was introduced by the libata merge trying to pull out all
the SFF code into a separate module.  Unfortunately, if you're a satapi
device you usually need to call atapi_request_sense, which has a bare
invocation of a SFF callback which is NULL on non-SFF HBAs.  Fix this by
making the call conditional.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index fedf62de9460..c16e3cea1d28 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2394,7 +2394,8 @@ static void atapi_request_sense(struct ata_queued_cmd *qc)
         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 
 #ifdef CONFIG_ATA_SFF
-        ap->ops->sff_tf_read(ap, &qc->tf);
+        if (ap->ops->sff_tf_read)
+                ap->ops->sff_tf_read(ap, &qc->tf);
 #endif
 
         /* fill these in, for the case where they are -not- overwritten */