[PATCH 05/11] block: drop custom queue draining used by scsi_transport_{iscsi|fc}

Tejun Heo
2012-04-26T22:02:19Z

iscsi_remove_host() uses bsg_remove_queue() which implements custom
queue draining. fc_bsg_remove() open-codes mostly identical logic.

The draining logic isn't correct in that blk_stop_queue() doesn't
prevent new requests from being queued - it just stops processing, so
nothing prevents new requests to be queued after the logic determines
that the queue is drained.

blk_cleanup_queue() now implements proper queue draining and these
custom draining logics aren't necessary. Drop them and use
bsg_unregister_queue() + blk_cleanup_queue() instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: James Smart <james.smart@emulex.com>
---
block/bsg-lib.c | 53 -----------------------------------
drivers/scsi/scsi_transport_fc.c | 38 -------------------------
drivers/scsi/scsi_transport_iscsi.c | 2 +-
include/linux/bsg-lib.h | 1 -
4 files changed, 1 insertions(+), 93 deletions(-)

diff --git a/block/bsg-lib.c b/block/bsg-lib.c
index 7ad49c8..deee61f 100644
--- a/block/bsg-lib.c
+++ b/block/bsg-lib.c
@@ -243,56 +243,3 @@ int bsg_setup_queue(struct device *dev, struct request_queue *q,
return 0;
}
EXPORT_SYMBOL_GPL(bsg_setup_queue);
-
-/**
- * bsg_remove_queue - Deletes the bsg dev from the q
- * @q: the request_queue that is to be torn down.
- *
- * Notes:
- * Before unregistering the queue empty any requests that are blocked
- */
-void bsg_remove_queue(struct request_queue *q)
-{
- struct request *req; /* block request */
- int counts; /* totals for request_list count and starved */
-
- if (!q)
- return;
-
- /* Stop taking in new requests */
- spin_lock_irq(q->queue_lock);
- blk_stop_queue(q);
-
- /* drain all requests in the queue */
- while (1) {
- /* need the lock to fetch a request
- * this may fetch the same reqeust as the previous pass
- */
- req = blk_fetch_request(q);
- /* save requests in use and starved */
- counts = q->rq.count[0] + q->rq.count[1] +
- q->rq.starved[0] + q->rq.starved[1];
- spin_unlock_irq(q->queue_lock);
- /* any requests still outstanding? */
- if (counts == 0)
- break;
-
- /* This may be the same req as the previous iteration,
- * always send the blk_end_request_all after a prefetch.
- * It is not okay to not end the request because the
- * prefetch started the request.
- */
- if (req) {
- /* return -ENXIO to indicate that this queue is
- * going away
- */
- req->errors = -ENXIO;
- blk_end_request_all(req, -ENXIO);
- }
-
- msleep(200); /* allow bsg to possibly finish */
- spin_lock_irq(q->queue_lock);
- }
- bsg_unregister_queue(q);
-}
-EXPORT_SYMBOL_GPL(bsg_remove_queue);
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 80fbe2a..3aff3db 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -4126,45 +4126,7 @@ fc_bsg_rportadd(struct Scsi_Host *shost, struct fc_rport *rport)
static void
fc_bsg_remove(struct request_queue *q)
{
- struct request *req; /* block request */
- int counts; /* totals for request_list count and starved */
-
if (q) {
- /* Stop taking in new requests */
- spin_lock_irq(q->queue_lock);
- blk_stop_queue(q);
-
- /* drain all requests in the queue */
- while (1) {
- /* need the lock to fetch a request
- * this may fetch the same reqeust as the previous pass
- */
- req = blk_fetch_request(q);
- /* save requests in use and starved */
- counts = q->rq.count[0] + q->rq.count[1] +
- q->rq.starved[0] + q->rq.starved[1];
- spin_unlock_irq(q->queue_lock);
- /* any requests still outstanding? */
- if (counts == 0)
- break;
-
- /* This may be the same req as the previous iteration,
- * always send the blk_end_request_all after a prefetch.
- * It is not okay to not end the request because the
- * prefetch started the request.
- */
- if (req) {
- /* return -ENXIO to indicate that this queue is
- * going away
- */
- req->errors = -ENXIO;
- blk_end_request_all(req, -ENXIO);
- }
-
- msleep(200); /* allow bsg to possibly finish */
- spin_lock_irq(q->queue_lock);
- }
-
bsg_unregister_queue(q);
blk_cleanup_queue(q);
}
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 1cf640e..c737a16 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -575,7 +575,7 @@ static int iscsi_remove_host(struct transport_container *tc,
struct iscsi_cls_host *ihost = shost->shost_data;

if (ihost->bsg_q) {
- bsg_remove_queue(ihost->bsg_q);
+ bsg_unregister_queue(ihost->bsg_q);
blk_cleanup_queue(ihost->bsg_q);
}
return 0;
diff --git a/include/linux/bsg-lib.h b/include/linux/bsg-lib.h
index f55ab8c..4d0fb3d 100644
--- a/include/linux/bsg-lib.h
+++ b/include/linux/bsg-lib.h
@@ -67,7 +67,6 @@ void bsg_job_done(struct bsg_job *job, int result,
int bsg_setup_queue(struct device *dev, struct request_queue *q, char *name,
bsg_job_fn *job_fn, int dd_job_size);
void bsg_request_fn(struct request_queue *q);
-void bsg_remove_queue(struct request_queue *q);
void bsg_goose_queue(struct request_queue *q);

#endif
--
1.7.7.3