On 06/26/2013 01:20 PM, Bart Van Assche wrote:
On 06/26/13 11:02, Maxim Uvarov wrote:
This fix:
end_request: I/O error, dev sdc, sector 976576
rport-0:0-3: blocked FC remote port time out: removing target and
saving
binding
BUG: unable to handle kernel NULL pointer dereference at
0000000000000400
IP: [<ffffffff812f0cc2>] scsi_prep_state_check+0xe/0x99
[<ffffffff812f1f9d>] scsi_setup_blk_pc_cmnd+0x1b/0x115
[<ffffffff812f20c0>] scsi_prep_fn+0x29/0x3b
[<ffffffff8121cfb9>] blk_peek_request+0xe1/0x1b3
[<ffffffff812f1400>] scsi_request_fn+0x3a/0x4d2
[<ffffffff8121d916>] __generic_unplug_device+0x32/0x36
[<ffffffff81220f4b>] blk_execute_rq_nowait+0x77/0x9e
[<ffffffff81221018>] blk_execute_rq+0xa6/0xde
[<ffffffff8144f24b>] ? printk+0x41/0x46
[<ffffffffa00a21c5>] ? get_rdac_req+0x81/0xe8 [scsi_dh_rdac]
[<ffffffffa00a273a>] send_mode_select+0x29f/0x489 [scsi_dh_rdac]
[<ffffffff810c5d9b>] ? probe_workqueue_execution+0xb1/0xce
[<ffffffff81071e38>] worker_thread+0x1a9/0x237
[<ffffffffa00a249b>] ? send_mode_select+0x0/0x489 [scsi_dh_rdac]
[<ffffffff8107651b>] ? autoremove_wake_function+0x0/0x39
[<ffffffff81071c8f>] ? worker_thread+0x0/0x237
[<ffffffff81076222>] kthread+0x7f/0x87
[<ffffffff81012d2a>] child_rip+0xa/0x20
[<ffffffff810761a3>] ? kthread+0x0/0x87
[<ffffffff81012d20>] ? child_rip+0x0/0x20
Signed-off-by: Maxim Uvarov <maxim.uvarov@xxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 86d5220..8e89ed9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1295,6 +1295,9 @@ int scsi_prep_fn(struct request_queue *q,
struct request *req)
struct scsi_device *sdev = q->queuedata;
int ret = BLKPREP_KILL;
+ if (!sdev)
+ return ret;
+
if (req->cmd_type == REQ_TYPE_BLOCK_PC)
ret = scsi_setup_blk_pc_cmnd(sdev, req);
return scsi_prep_return(q, req, ret);
Sorry but this patch does not look like a proper fix to me. What you
probably need is a scsi_device_get() call in scsi_dh_rdac.c somewhere
before the queue_work(kmpath_rdacd, &ctlr->ms_work) call and a
scsi_device_put() call once send_mode_select() has finished using the
sdev.
Bart.
Thanks Bart. It looks reasonable. I will do some testing for your solution.
Maxim.
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