On Mon, 2008-12-01 at 18:04 -0800, Nicholas A. Bellinger wrote: > On Mon, 2008-12-01 at 17:52 -0800, Nicholas A. Bellinger wrote: > > Greetings Tomo-san and Co, > > > > With the ongoing work in Linux/SCSI for v2.6.28 to map target mode > > struct scatterlist memory directly down to struct scsi_cmnd without the > > need for a intermediate struct bio as with the existing > > scsi_execute_async(), I have started the porting process for the > > Linux/SCSI subsystem plugin in generic target core v3.0 > > (lio-core-2.6.git) on v2.6.28-rc6. > > > > So far, using struct request for ICF_SCSI_CONTROL_NONSG_IO_CDB is up > > using blk_rq_map_kern(), as well as ICF_SCSI_NON_DATA_CDB ops using > > struct request. In order to get the first READ_10s of type > > ICF_SCSI_DATA_SG_IO_CDB to work, I had to add a temporary > > EXPORT_SYMBOL_GPL() for drivers/scsi/scsi_lib.c:scsi_req_map_sg() in > > lio-core-2.6.git for v2.6.28-rc6 in order to get TYPE_DISK up using an > > software emulated MPT-Fusion HBA driver with struct request. I have > > been looking at drivers/scsi/scsi_tgt_lib.c() (which currently uses > > struct request), and I figure we need something similar for the generic > > target infrastructure, although __scsi_get_command() and > > __scsi_put_command() are currently used in that code. > > > > Below is what my patch looks like so far, I will probably just end up > > commiting an temporary ifdef to keep scsi_execute_async() until the > > proper pieces are in place and the other issues are resolved below. > > >From there I will be able to drop in the proper upstream mapping bits > > for struct scatterlist in > > drivers/lio-core/target_core_pscsi.c:pscsi_map_task_SG() get rid of > > scsi_req_map_sg() usage all together. > > > > So far during my initial testing, I am running into a two different > > exceptions. One NULL pointer deference OOPS after half dozen Open/iSCSI > > login/logouts in block/elevator.c:elv_dequeue_request(). Here is the > > trace from SCSI softirq context: > > > > http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-0.png > > http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-1.png > > > > The other one is a BUG_ON in blk/blk-timeout.c:177 in blk_add_timeout() > > that happens after a few hundred MB of READ_10 traffic, which also > > appears to pass through elv_dequeue_request() at some point: > > > > http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-2.png > > http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-4.png > > > > Ok, I just saw this patch: > > [PATCH 2.6.28-rc6] block: internal dequeue shouldn't start timer > > at http://lkml.org/lkml/2008/11/27/394. > > It sounds very similar and I will try it out and see if it resolves the > issues above. > Ok, patch applied and rerunning, this time after ~20 Open/iSCSI --login/--logout ops. The same BUG_ON in blk/blk-timeout.c:177 in blk_add_timeout() again triggered again, this time coming from blkdev_dequeue_request() -> scsi_request_fn() -> __generic_unplugin_device(). http://linux-iscsi.org/builds/user/nab/2.6.28-rc6-oops-5.png blkdev_dequeue_request() is used in a few other places in drivers/scsi: target:/mnt/sdb/lio-core-2.6/drivers/scsi# grep blkdev_dequeue_request * Binary file built-in.o matches scsi_lib.c: blkdev_dequeue_request(req); scsi_lib.c: blkdev_dequeue_request(req); Binary file scsi_lib.o matches Binary file scsi_mod.o matches scsi_transport_sas.c: blkdev_dequeue_request(req); Do these need to be changed to use elv_dequeue_request() as well..? --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
