diff options
| author | Tahsin Erdogan <tahsin@google.com> | 2017-02-14 19:27:38 -0800 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-02-15 08:40:04 -0700 |
| commit | b410aff2bd9f101bc096069612391aecce204cd1 (patch) | |
| tree | 977805735b8ce122d67da721e8a960c15ef89769 /block | |
| parent | 3d492c2e0146ccaad08c7cbe16e2e229328b5e79 (diff) | |
| download | lwn-b410aff2bd9f101bc096069612391aecce204cd1.tar.gz lwn-b410aff2bd9f101bc096069612391aecce204cd1.zip | |
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')
| -rw-r--r-- | block/blk-sysfs.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 070d81bae1d5..002af836aa87 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) |