On Thu, Jan 09, 2025 at 01:07:47PM +0000, John Garry wrote: > Do you mean that the sysfs_lock could be removed in future? I would have > thought that queue limits lock could be used for the same thing, but I am > probably failing to see some lock nesting/ordering issues... More or less. Think about it: what does it even try to protect? Readіng/writing sysfs files vs itself and file removal it serialized by sysfs/kernfs internally. Any information tweaked in sysfs usually also has other places that can modify it. So we'll need a lock independent of sysfs for that anyway. A big part, buy by far all of that is covered by limits_lock. Serializing creating/removing sysfs attribues is supposed to be serialized using sysfs_dir_lock, although that needs a careful audit. It's also used to serialize a few debugfs things, but we'll need to look carefully for what exactly and switch that over to debugfs_mutex or something new. And then there's a bunch of misc cruft that also needs a careful look.
