Hi,
On 2020/2/13 5:33, Tejun Heo wrote:
So, I don't see why bdi->dev should be freed before bdi itself does.
Would something like the following work?
bdi_unregister()
{
...
if (bdi->dev) {
...
device_get(bdi->dev); // to be put on release
device_unregister(bdi->dev);
}
...
}
release_bdi()
{
...
if (bdi->dev) {
// warn if dev is still registered
device_put(bdi->dev);
}
...
}
For each time of register, bdi_register() will try to create a new 'dev'.
bdi_register
bdi_register_va
if (bdi->dev) // if bdi->dev is not NULL, return directly
return 0;
dev = device_create_vargs()...
So, I think freeing bdi->dev until bdi itself does may be a problem
for drivers that supported re-registration bdi, such as:
commit b6f8fec4448aa52a8c36a392aa1ca2ea99acd460
Author: Jan Kara <jack@xxxxxxx>
Date: Wed Mar 8 17:48:31 2017 +0100
block: Allow bdi re-registration
SCSI can call device_add_disk() several times for one request queue when
a device in unbound and bound, creating new gendisk each time. This will
lead to bdi being repeatedly registered and unregistered.
