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authorTahsin Erdogan <tahsin@google.com>2017-02-14 19:27:38 -0800
committerJens Axboe <axboe@fb.com>2017-02-15 08:40:04 -0700
commitb410aff2bd9f101bc096069612391aecce204cd1 (patch)
tree977805735b8ce122d67da721e8a960c15ef89769 /block/blk-sysfs.c
parent3d492c2e0146ccaad08c7cbe16e2e229328b5e79 (diff)
downloadlinux-0-day-b410aff2bd9f101bc096069612391aecce204cd1.tar.gz
block: do not allow updates through sysfs until registration completes
When a new disk shows up, sysfs queue directory is created before elevator is registered. This allows a user to attempt a scheduler switch even though the initial registration hasn't completed yet. In one scenario, blk_register_queue() calls elv_register_queue() and right before cfq_registered_queue() is called, another process executes elevator_switch() and replaces q->elevator with deadline scheduler. When cfq_registered_queue() executes it interprets e->elevator_data as struct cfq_data even though it is actually struct deadline_data. Grab q->sysfs_lock in blk_register_queue() to synchronize with sysfs callers. Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-sysfs.c')
-rw-r--r--block/blk-sysfs.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 070d81b..002af83 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -902,17 +902,20 @@ int blk_register_queue(struct gendisk *disk)
if (ret)
return ret;
+ if (q->mq_ops)
+ blk_mq_register_dev(dev, q);
+
+ /* Prevent changes through sysfs until registration is completed. */
+ mutex_lock(&q->sysfs_lock);
+
ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
if (ret < 0) {
blk_trace_remove_sysfs(dev);
- return ret;
+ goto unlock;
}
kobject_uevent(&q->kobj, KOBJ_ADD);
- if (q->mq_ops)
- blk_mq_register_dev(dev, q);
-
blk_wb_init(q);
if (q->request_fn || (q->mq_ops && q->elevator)) {
@@ -922,11 +925,13 @@ int blk_register_queue(struct gendisk *disk)
kobject_del(&q->kobj);
blk_trace_remove_sysfs(dev);
kobject_put(&dev->kobj);
- return ret;
+ goto unlock;
}
}
-
- return 0;
+ ret = 0;
+unlock:
+ mutex_unlock(&q->sysfs_lock);
+ return ret;
}
void blk_unregister_queue(struct gendisk *disk)