Re: [PATCH-tip v7 00/20] locking/rwsem: Rwsem rearchitecture part 2

[Waiman Long <longman@redhat.com>]

On 4/28/19 7:12 PM, Waiman Long wrote:
> On 4/28/19 6:46 PM, Linus Torvalds wrote:
>> This doesn't seem to be the full diff - looking at that patch 1 you
>> seem to have taken my suggested list_cut_before() change too.
>>
>> I'm not against it (it does seem to be simpler and better), I just
>> hope you double-checked it, since I kind of hand-waved it.
>>
>>                     Linus
> I implemented your suggestion in patch 1 as it will produce simpler and
> faster code. However, one of the changes in my patchset is to wake up
> all the readers in the wait list. This means I have to jump over the
> writers and wake up the readers behind them as well. See patch 11 for
> details. As a result, I have to revert back to use list_add_tail() and
> list_for_each_entry_safe() for the first pass. That is why the diff for
> the whole patchset is just the below change. It is done on purpose, not
> an omission.

That is also the reason why it was implemented this way in my v6
patchset. I implemented the fix on top of the rwsem patchset first and
then move it backward to the beginning of the patchset for easier backport.

Cheers,
Longman