block: make queue flags non-atomic
We can save some atomic ops in the IO path, if we clearly define
the rules of how to modify the queue flags.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f7f1635..d3a25b0 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -546,7 +546,7 @@
{
struct loop_device *lo = q->queuedata;
- clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
+ queue_flag_clear_unlocked(QUEUE_FLAG_PLUGGED, q);
blk_run_address_space(lo->lo_backing_file->f_mapping);
}
diff --git a/drivers/block/ub.c b/drivers/block/ub.c
index 27bfe72..e322cce 100644
--- a/drivers/block/ub.c
+++ b/drivers/block/ub.c
@@ -2399,7 +2399,7 @@
del_gendisk(lun->disk);
/*
* I wish I could do:
- * set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
+ * queue_flag_set(QUEUE_FLAG_DEAD, q);
* As it is, we rely on our internal poisoning and let
* the upper levels to spin furiously failing all the I/O.
*/
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 51be533..73326e7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -873,10 +873,13 @@
q->max_hw_sectors = t->limits.max_hw_sectors;
q->seg_boundary_mask = t->limits.seg_boundary_mask;
q->bounce_pfn = t->limits.bounce_pfn;
+ /* XXX: the below will probably go bug. must ensure there can be no
+ * concurrency on queue_flags, and use the unlocked versions...
+ */
if (t->limits.no_cluster)
- q->queue_flags &= ~(1 << QUEUE_FLAG_CLUSTER);
+ queue_flag_clear(QUEUE_FLAG_CLUSTER, q);
else
- q->queue_flags |= (1 << QUEUE_FLAG_CLUSTER);
+ queue_flag_set(QUEUE_FLAG_CLUSTER, q);
}
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 87620b7..acd716b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -282,7 +282,8 @@
kfree(new);
return NULL;
}
- set_bit(QUEUE_FLAG_CLUSTER, &new->queue->queue_flags);
+ /* Can be unlocked because the queue is new: no concurrency */
+ queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, new->queue);
blk_queue_make_request(new->queue, md_fail_request);
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 07103c3..f6600bf 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1773,7 +1773,7 @@
if (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts)
printk(KERN_INFO "scsi_debug: slave_alloc <%u %u %u %u>\n",
sdp->host->host_no, sdp->channel, sdp->id, sdp->lun);
- set_bit(QUEUE_FLAG_BIDI, &sdp->request_queue->queue_flags);
+ queue_flag_set_unlocked(QUEUE_FLAG_BIDI, sdp->request_queue);
return 0;
}
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 67f412b..d545ad1 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -536,6 +536,9 @@
!shost->host_blocked && !shost->host_self_blocked &&
!((shost->can_queue > 0) &&
(shost->host_busy >= shost->can_queue))) {
+
+ int flagset;
+
/*
* As long as shost is accepting commands and we have
* starved queues, call blk_run_queue. scsi_request_fn
@@ -549,19 +552,20 @@
sdev = list_entry(shost->starved_list.next,
struct scsi_device, starved_entry);
list_del_init(&sdev->starved_entry);
- spin_unlock_irqrestore(shost->host_lock, flags);
+ spin_unlock(shost->host_lock);
+ spin_lock(sdev->request_queue->queue_lock);
+ flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
+ !test_bit(QUEUE_FLAG_REENTER,
+ &sdev->request_queue->queue_flags);
+ if (flagset)
+ queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
+ __blk_run_queue(sdev->request_queue);
+ if (flagset)
+ queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
+ spin_unlock(sdev->request_queue->queue_lock);
- if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
- !test_and_set_bit(QUEUE_FLAG_REENTER,
- &sdev->request_queue->queue_flags)) {
- blk_run_queue(sdev->request_queue);
- clear_bit(QUEUE_FLAG_REENTER,
- &sdev->request_queue->queue_flags);
- } else
- blk_run_queue(sdev->request_queue);
-
- spin_lock_irqsave(shost->host_lock, flags);
+ spin_lock(shost->host_lock);
if (unlikely(!list_empty(&sdev->starved_entry)))
/*
* sdev lost a race, and was put back on the
@@ -1585,8 +1589,9 @@
blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
+ /* New queue, no concurrency on queue_flags */
if (!shost->use_clustering)
- clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+ queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
/*
* set a reasonable default alignment on word boundaries: the
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 7899e3d..f4461d3 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -248,8 +248,7 @@
else
q->queuedata = shost;
- set_bit(QUEUE_FLAG_BIDI, &q->queue_flags);
-
+ queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
return 0;
}