Messages in this thread | | | Date | Thu, 27 Jun 2013 12:47:56 +0400 | From | Maxim Uvarov <> | Subject | Re: [PATCH] scsi_prep_fn() check for empty queue |
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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@oracle.com> >> --- >> 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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