• Tahsin Erdogan's avatar
    block: do not allow updates through sysfs until registration completes · b410aff2
    Tahsin Erdogan authored
    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
    Signed-off-by: default avatarTahsin Erdogan <tahsin@google.com>
    Signed-off-by: default avatarJens Axboe <axboe@fb.com>
blk-sysfs.c 23.3 KB