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-rw-r--r--drivers/block/xen-blkback/common.h4
-rw-r--r--drivers/block/xen-blkback/xenbus.c46
2 files changed, 36 insertions, 14 deletions
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index be052773ad03..f65b807e3236 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -314,7 +314,7 @@ struct xen_blkif {
unsigned long long st_rd_sect;
unsigned long long st_wr_sect;
- wait_queue_head_t waiting_to_free;
+ struct work_struct free_work;
/* Thread shutdown wait queue. */
wait_queue_head_t shutdown_wq;
};
@@ -361,7 +361,7 @@ struct pending_req {
#define xen_blkif_put(_b) \
do { \
if (atomic_dec_and_test(&(_b)->refcnt)) \
- wake_up(&(_b)->waiting_to_free);\
+ schedule_work(&(_b)->free_work);\
} while (0)
struct phys_req {
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index a71ecf5f4283..3a8b810b4980 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -35,12 +35,26 @@ static void connect(struct backend_info *);
static int connect_ring(struct backend_info *);
static void backend_changed(struct xenbus_watch *, const char **,
unsigned int);
+static void xen_blkif_free(struct xen_blkif *blkif);
+static void xen_vbd_free(struct xen_vbd *vbd);
struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
{
return be->dev;
}
+/*
+ * The last request could free the device from softirq context and
+ * xen_blkif_free() can sleep.
+ */
+static void xen_blkif_deferred_free(struct work_struct *work)
+{
+ struct xen_blkif *blkif;
+
+ blkif = container_of(work, struct xen_blkif, free_work);
+ xen_blkif_free(blkif);
+}
+
static int blkback_name(struct xen_blkif *blkif, char *buf)
{
char *devpath, *devname;
@@ -121,7 +135,6 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
init_completion(&blkif->drain_complete);
atomic_set(&blkif->drain, 0);
blkif->st_print = jiffies;
- init_waitqueue_head(&blkif->waiting_to_free);
blkif->persistent_gnts.rb_node = NULL;
spin_lock_init(&blkif->free_pages_lock);
INIT_LIST_HEAD(&blkif->free_pages);
@@ -132,6 +145,7 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
INIT_LIST_HEAD(&blkif->pending_free);
+ INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
for (i = 0; i < XEN_BLKIF_REQS; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
@@ -231,7 +245,7 @@ static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
return 0;
}
-static void xen_blkif_disconnect(struct xen_blkif *blkif)
+static int xen_blkif_disconnect(struct xen_blkif *blkif)
{
if (blkif->xenblkd) {
kthread_stop(blkif->xenblkd);
@@ -239,9 +253,12 @@ static void xen_blkif_disconnect(struct xen_blkif *blkif)
blkif->xenblkd = NULL;
}
- atomic_dec(&blkif->refcnt);
- wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
- atomic_inc(&blkif->refcnt);
+ /* The above kthread_stop() guarantees that at this point we
+ * don't have any discard_io or other_io requests. So, checking
+ * for inflight IO is enough.
+ */
+ if (atomic_read(&blkif->inflight) > 0)
+ return -EBUSY;
if (blkif->irq) {
unbind_from_irqhandler(blkif->irq, blkif);
@@ -252,6 +269,8 @@ static void xen_blkif_disconnect(struct xen_blkif *blkif)
xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
blkif->blk_rings.common.sring = NULL;
}
+
+ return 0;
}
static void xen_blkif_free(struct xen_blkif *blkif)
@@ -259,8 +278,8 @@ static void xen_blkif_free(struct xen_blkif *blkif)
struct pending_req *req, *n;
int i = 0, j;
- if (!atomic_dec_and_test(&blkif->refcnt))
- BUG();
+ xen_blkif_disconnect(blkif);
+ xen_vbd_free(&blkif->vbd);
/* Remove all persistent grants and the cache of ballooned pages. */
xen_blkbk_free_caches(blkif);
@@ -449,16 +468,15 @@ static int xen_blkbk_remove(struct xenbus_device *dev)
be->backend_watch.node = NULL;
}
+ dev_set_drvdata(&dev->dev, NULL);
+
if (be->blkif) {
xen_blkif_disconnect(be->blkif);
- xen_vbd_free(&be->blkif->vbd);
- xen_blkif_free(be->blkif);
- be->blkif = NULL;
+ xen_blkif_put(be->blkif);
}
kfree(be->mode);
kfree(be);
- dev_set_drvdata(&dev->dev, NULL);
return 0;
}
@@ -705,7 +723,11 @@ static void frontend_changed(struct xenbus_device *dev,
* Enforce precondition before potential leak point.
* xen_blkif_disconnect() is idempotent.
*/
- xen_blkif_disconnect(be->blkif);
+ err = xen_blkif_disconnect(be->blkif);
+ if (err) {
+ xenbus_dev_fatal(dev, err, "pending I/O");
+ break;
+ }
err = connect_ring(be);
if (err)