On Mon, 2008-12-01 at 19:10 -0800, Nicholas A. Bellinger wrote: > 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..? > Ok, I am up and running using the following patch against v2.6.28-rc6 (along with Tejun's patch). Comments please..? diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f5d3b96..77f1fe0 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1505,7 +1507,7 @@ static void scsi_kill_request(struct request *req, struct request_queue *q) struct scsi_target *starget = scsi_target(sdev); struct Scsi_Host *shost = sdev->host; - blkdev_dequeue_request(req); + elv_dequeue_request(req->q, req); if (unlikely(cmd == NULL)) { printk(KERN_CRIT "impossible request in %s.\n", @@ -1634,7 +1636,7 @@ static void scsi_request_fn(struct request_queue *q) * Remove the request from the request list. */ if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) - blkdev_dequeue_request(req); + elv_dequeue_request(req->q, req); sdev->device_busy++; spin_unlock(q->queue_lock); Also, blkdev_dequeue_request() is still used in drivers/scsi/scsi_transport_sas.c().. Thanks, --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
