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path: root/drivers/block/xen-blkback/xenbus.c
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Diffstat (limited to 'drivers/block/xen-blkback/xenbus.c')
-rw-r--r--drivers/block/xen-blkback/xenbus.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 5dfe6e8af140..1d1f86657967 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -178,6 +178,15 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid)
blkif->domid = domid;
atomic_set(&blkif->refcnt, 1);
init_completion(&blkif->drain_complete);
+
+ /*
+ * Because freeing back to the cache may be deferred, it is not
+ * safe to unload the module (and hence destroy the cache) until
+ * this has completed. To prevent premature unloading, take an
+ * extra module reference here and release only when the object
+ * has been freed back to the cache.
+ */
+ __module_get(THIS_MODULE);
INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
return blkif;
@@ -322,6 +331,7 @@ static void xen_blkif_free(struct xen_blkif *blkif)
/* Make sure everything is drained before shutting down */
kmem_cache_free(xen_blkif_cachep, blkif);
+ module_put(THIS_MODULE);
}
int __init xen_blkif_interface_init(void)
@@ -967,6 +977,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
}
blkif->nr_ring_pages = nr_grefs;
+ err = -ENOMEM;
for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (!req)
@@ -989,7 +1000,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);
if (err) {
xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
- return err;
+ goto fail;
}
return 0;
@@ -1009,8 +1020,7 @@ fail:
}
kfree(req);
}
- return -ENOMEM;
-
+ return err;
}
static int connect_ring(struct backend_info *be)