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Date: Sat, 5 Sep 2015 20:39:38 +0800
From: Bob Liu <bob.liu@...cle.com>
To: xen-devel@...ts.xen.org
Cc: david.vrabel@...rix.com, linux-kernel@...r.kernel.org,
roger.pau@...rix.com, konrad.wilk@...cle.com,
felipe.franciosi@...rix.com, axboe@...com, hch@...radead.org,
avanzini.arianna@...il.com, rafal.mielniczuk@...rix.com,
boris.ostrovsky@...cle.com, jonathan.davies@...rix.com,
Bob Liu <bob.liu@...cle.com>
Subject: [PATCH v3 5/9] xen/blkfront: convert per device io_lock to per ring ring_lock
The per device io_lock became a coarser grained lock after multi-queues/rings
was introduced, this patch converts it to a fine-grained per ring lock.
NOTE: The per dev_info structure was no more protected by any lock.
Signed-off-by: Bob Liu <bob.liu@...cle.com>
---
drivers/block/xen-blkfront.c | 44 +++++++++++++++++++-----------------------
1 file changed, 20 insertions(+), 24 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index bf45c99..1cae76b 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -123,6 +123,7 @@ MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the
struct blkfront_ring_info
{
struct blkif_front_ring ring;
+ spinlock_t ring_lock;
unsigned int ring_ref[XENBUS_MAX_RING_PAGES];
unsigned int evtchn, irq;
struct work_struct work;
@@ -141,7 +142,6 @@ struct blkfront_ring_info
* putting all kinds of interesting stuff here :-)
*/
struct blkfront_dev_info {
- spinlock_t io_lock;
struct mutex mutex;
struct xenbus_device *xbdev;
struct gendisk *gd;
@@ -637,29 +637,28 @@ static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *qd)
{
struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)hctx->driver_data;
- struct blkfront_dev_info *dinfo = rinfo->dinfo;
blk_mq_start_request(qd->rq);
- spin_lock_irq(&dinfo->io_lock);
+ spin_lock_irq(&rinfo->ring_lock);
if (RING_FULL(&rinfo->ring))
goto out_busy;
- if (blkif_request_flush_invalid(qd->rq, dinfo))
+ if (blkif_request_flush_invalid(qd->rq, rinfo->dinfo))
goto out_err;
if (blkif_queue_request(qd->rq, rinfo))
goto out_busy;
flush_requests(rinfo);
- spin_unlock_irq(&dinfo->io_lock);
+ spin_unlock_irq(&rinfo->ring_lock);
return BLK_MQ_RQ_QUEUE_OK;
out_err:
- spin_unlock_irq(&dinfo->io_lock);
+ spin_unlock_irq(&rinfo->ring_lock);
return BLK_MQ_RQ_QUEUE_ERROR;
out_busy:
- spin_unlock_irq(&dinfo->io_lock);
+ spin_unlock_irq(&rinfo->ring_lock);
blk_mq_stop_hw_queue(hctx);
return BLK_MQ_RQ_QUEUE_BUSY;
}
@@ -961,7 +960,7 @@ static void xlvbd_release_gendisk(struct blkfront_dev_info *dinfo)
dinfo->gd = NULL;
}
-/* Must be called with io_lock holded */
+/* Must be called with ring_lock holded */
static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
{
if (!RING_FULL(&rinfo->ring))
@@ -972,10 +971,10 @@ static void blkif_restart_queue(struct work_struct *work)
{
struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
- spin_lock_irq(&rinfo->dinfo->io_lock);
+ spin_lock_irq(&rinfo->ring_lock);
if (rinfo->dinfo->connected == BLKIF_STATE_CONNECTED)
kick_pending_request_queues(rinfo);
- spin_unlock_irq(&rinfo->dinfo->io_lock);
+ spin_unlock_irq(&rinfo->ring_lock);
}
static void blkif_free(struct blkfront_dev_info *dinfo, int suspend)
@@ -986,7 +985,6 @@ static void blkif_free(struct blkfront_dev_info *dinfo, int suspend)
struct blkfront_ring_info *rinfo;
/* Prevent new requests being issued until we fix things up. */
- spin_lock_irq(&dinfo->io_lock);
dinfo->connected = suspend ?
BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
/* No more blkif_request(). */
@@ -996,6 +994,7 @@ static void blkif_free(struct blkfront_dev_info *dinfo, int suspend)
for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
rinfo = &dinfo->rinfo[r_index];
+ spin_lock_irq(&rinfo->ring_lock);
/* Remove all persistent grants */
if (!list_empty(&rinfo->grants)) {
list_for_each_entry_safe(persistent_gnt, n,
@@ -1071,7 +1070,7 @@ free_shadow:
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&rinfo->callback);
- spin_unlock_irq(&dinfo->io_lock);
+ spin_unlock_irq(&rinfo->ring_lock);
/* Flush gnttab callback work. Must be done with no locks held. */
flush_work(&rinfo->work);
@@ -1180,13 +1179,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
struct blkfront_dev_info *dinfo = rinfo->dinfo;
- spin_lock_irqsave(&dinfo->io_lock, flags);
-
- if (unlikely(dinfo->connected != BLKIF_STATE_CONNECTED)) {
- spin_unlock_irqrestore(&dinfo->io_lock, flags);
+ if (unlikely(dinfo->connected != BLKIF_STATE_CONNECTED))
return IRQ_HANDLED;
- }
+ spin_lock_irqsave(&rinfo->ring_lock, flags);
again:
rp = rinfo->ring.sring->rsp_prod;
rmb(); /* Ensure we see queued responses up to 'rp'. */
@@ -1279,7 +1275,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
kick_pending_request_queues(rinfo);
- spin_unlock_irqrestore(&dinfo->io_lock, flags);
+ spin_unlock_irqrestore(&rinfo->ring_lock, flags);
return IRQ_HANDLED;
}
@@ -1534,7 +1530,6 @@ static int blkfront_probe(struct xenbus_device *dev,
}
mutex_init(&dinfo->mutex);
- spin_lock_init(&dinfo->io_lock);
dinfo->xbdev = dev;
dinfo->vdevice = vdevice;
dinfo->connected = BLKIF_STATE_DISCONNECTED;
@@ -1550,6 +1545,7 @@ static int blkfront_probe(struct xenbus_device *dev,
for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
rinfo = &dinfo->rinfo[r_index];
+ spin_lock_init(&rinfo->ring_lock);
INIT_LIST_HEAD(&rinfo->grants);
INIT_LIST_HEAD(&rinfo->indirect_pages);
rinfo->persistent_gnts_c = 0;
@@ -1650,16 +1646,16 @@ static int blkif_recover(struct blkfront_dev_info *dinfo)
xenbus_switch_state(dinfo->xbdev, XenbusStateConnected);
- spin_lock_irq(&dinfo->io_lock);
-
/* Now safe for us to use the shared ring */
dinfo->connected = BLKIF_STATE_CONNECTED;
for (r_index = 0; r_index < dinfo->nr_rings; r_index++) {
rinfo = &dinfo->rinfo[r_index];
+ spin_lock_irq(&rinfo->ring_lock);
/* Kick any other new requests queued since we resumed */
kick_pending_request_queues(rinfo);
+ spin_unlock_irq(&rinfo->ring_lock);
}
list_for_each_entry_safe(req, n, &requests, queuelist) {
@@ -1668,7 +1664,6 @@ static int blkif_recover(struct blkfront_dev_info *dinfo)
BUG_ON(req->nr_phys_segments > segs);
blk_mq_requeue_request(req);
}
- spin_unlock_irq(&dinfo->io_lock);
blk_mq_kick_requeue_list(dinfo->rq);
while ((bio = bio_list_pop(&bio_list)) != NULL) {
@@ -2049,13 +2044,14 @@ static void blkfront_connect(struct blkfront_dev_info *dinfo)
xenbus_switch_state(dinfo->xbdev, XenbusStateConnected);
/* Kick pending requests. */
- spin_lock_irq(&dinfo->io_lock);
dinfo->connected = BLKIF_STATE_CONNECTED;
for (i = 0; i < dinfo->nr_rings; i++) {
rinfo = &dinfo->rinfo[i];
+
+ spin_lock_irq(&rinfo->ring_lock);
kick_pending_request_queues(rinfo);
+ spin_unlock_irq(&rinfo->ring_lock);
}
- spin_unlock_irq(&dinfo->io_lock);
add_disk(dinfo->gd);
--
1.7.10.4
--
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