[PATCH 3/3] ide-{cd,floppy}: do not map all cmds to an sg

[Borislav Petkov <petkovbb@googlemail.com>]

... since some do not transfer any data from the drive and
rq->buffer is unset leading to an OOPS when checking VM translations
(CONFIG_DEBUG_VIRTUAL).

Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-atapi.c  |    9 ++++++++-
 drivers/ide/ide-cd.c     |    4 ----
 drivers/ide/ide-floppy.c |    4 ----
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
index a5596a6..ef78cbf 100644
--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -570,7 +570,7 @@ static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 
 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 {
-	struct ide_atapi_pc *pc;
+	struct ide_atapi_pc *uninitialized_var(pc);
 	ide_hwif_t *hwif = drive->hwif;
 	ide_expiry_t *expiry = NULL;
 	struct request *rq = hwif->rq;
@@ -587,6 +587,7 @@ ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 
 		if (drive->dma)
 			drive->dma = !ide_dma_prepare(drive, cmd);
+
 	} else {
 		pc = drive->pc;
 
@@ -614,6 +615,12 @@ ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 						       : WAIT_TAPE_CMD;
 	}
 
+	if (drive->media != ide_tape &&
+	      !drive->dma && (blk_fs_request(rq) || rq->data_len)) {
+		ide_init_sg_cmd(cmd, blk_rq_bytes(rq));
+		ide_map_sg(drive, cmd);
+	}
+
 	ide_init_packet_cmd(cmd, tf_flags, bcount, drive->dma);
 
 	(void)do_rw_taskfile(drive, cmd);
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 091d414..106cacb 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -916,10 +916,6 @@ static ide_startstop_t ide_cd_do_request(ide_drive_t *drive, struct request *rq,
 
 	cmd.rq = rq;
 
-	ide_init_sg_cmd(&cmd,
-		blk_fs_request(rq) ? (rq->nr_sectors << 9) : rq->data_len);
-	ide_map_sg(drive, &cmd);
-
 	return ide_issue_pc(drive, &cmd);
 out_end:
 	nsectors = rq->hard_nr_sectors;
diff --git a/drivers/ide/ide-floppy.c b/drivers/ide/ide-floppy.c
index 2f8f453..b91deef 100644
--- a/drivers/ide/ide-floppy.c
+++ b/drivers/ide/ide-floppy.c
@@ -281,10 +281,6 @@ static ide_startstop_t ide_floppy_do_request(ide_drive_t *drive,
 		cmd.tf_flags |= IDE_TFLAG_WRITE;
 
 	cmd.rq = rq;
-
-	ide_init_sg_cmd(&cmd, pc->req_xfer);
-	ide_map_sg(drive, &cmd);
-
 	pc->rq = rq;
 
 	return ide_floppy_issue_pc(drive, &cmd, pc);
-- 
1.6.1.3