[PATCH] Initialise scatter/gather list in sg driver

Anton Blanchard
2007-10-25T19:31:07Z

After turning on DEBUG_SG I hit a fail:

kernel BUG at include/linux/scatterlist.h:50!

ata_qc_issue
ata_scsi_translate
ipr_queuecommand
scsi_dispatch_cmd
scsi_request_fn
elv_insert
blk_execute_rq_nowait
blk_execute_rq
sg_io
scsi_cmd_ioctl
cdrom_ioctl
sr_block_ioctl
blkdev_driver_ioctl
blkdev_ioctl
block_ioctl
do_ioctl
vfs_ioctl
sys_ioctl
sg_ioctl_trans

It looks like ata_sg_setup is working on an uninitialised sg table. Call
sg_init_table to initialise it before use.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

Jens this is against your sg branch. This fixes the fail but Id
appreciate a confirmation that it's the right fix :)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index b5f7c59..4de41bb 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4689,6 +4689,7 @@ static int ata_sg_setup(struct ata_queued_cmd *qc)
* data in this function or read data in ata_sg_clean.
*/
offset = lsg->offset + lsg->length - qc->pad_len;
+ sg_init_table(psg, 1);
sg_set_page(psg, nth_page(sg_page(lsg), offset >> PAGE_SHIFT),
qc->pad_len, offset_in_page(offset));