Re: [PATCH 03/32] locking/lockdep: lockdep_set_no_check_recursion()

Waiman Long
2023-05-09T20:28:42Z

On 5/9/23 16:18, Kent Overstreet wrote:
> On Tue, May 09, 2023 at 09:31:47PM +0200, Peter Zijlstra wrote:
>> On Tue, May 09, 2023 at 12:56:28PM -0400, Kent Overstreet wrote:
>>> This adds a method to tell lockdep not to check lock ordering within a
>>> lock class - but to still check lock ordering w.r.t. other lock types.
>>>
>>> This is for bcachefs, where for btree node locks we have our own
>>> deadlock avoidance strategy w.r.t. other btree node locks (cycle
>>> detection), but we still want lockdep to check lock ordering w.r.t.
>>> other lock types.
>>>
>> ISTR you had a much nicer version of this where you gave a custom order
>> function -- what happend to that?
> Actually, I spoke too soon; this patch and the other series with the
> comparison function solve different problems.
>
> For bcachefs btree node locks, we don't have a defined lock ordering at
> all - we do full runtime cycle detection, so we don't want lockdep
> checking for self deadlock because we're handling that but we _do_ want
> lockdep checking lock ordering of btree node locks w.r.t. other locks in
> the system.

Maybe you can use lock_set_novalidate_class() instead.

Cheers,
Longman