Hello, On Thu, Jan 05, 2023 at 09:35:21AM +0800, Yu Kuai wrote: > > Can you please take a look at the following patchset I just posted: > > > > https://lkml.kernel.org/r/20230105002007.157497-1-tj@xxxxxxxxxx > > > > After that, all these configuration operations are wrapped between > > blkg_conf_init() and blkg_conf_exit() which probably are the right place to > > implement the synchronization. > > I see that, blkg_conf_init() and blkg_conf_exit() is good, however there > are some details I want to confirm: > > 1) rq_qos_add() can be called from iocost/iolatency, where > blkg_conf_init() will be called first, while rq_qos_add() can also be > called from wbt, where there is no blkg_conf_init(). Hence it seems to > me we need two locks here, one to protect rq_qos apis; one to > synchronize policy configuration and device removal. wbt's lazy init is tied to one of the block device sysfs files, right? So, it *should* already be protected against device removal. Thanks. -- tejun
