Messages in this thread | | | From | "Byungchul Park" <> | Subject | RE: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation | Date | Wed, 30 Aug 2017 18:35:07 +0900 |
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> -----Original Message----- > From: Peter Zijlstra [mailto:peterz@infradead.org] > Sent: Wednesday, August 30, 2017 6:14 PM > To: Byungchul Park > Cc: mingo@kernel.org; tj@kernel.org; boqun.feng@gmail.com; > david@fromorbit.com; johannes@sipsolutions.net; oleg@redhat.com; linux- > kernel@vger.kernel.org; kernel-team@lge.com > Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation > > On Wed, Aug 30, 2017 at 11:12:23AM +0200, Peter Zijlstra wrote: > > On Wed, Aug 30, 2017 at 06:01:59PM +0900, Byungchul Park wrote: > > > My point is that we inevitably lose valuable dependencies by yours. > That's > > > why I've endlessly asked you 'do you have any reason you try those > patches?' > > > a ton of times. And you have never answered it. > > > > The only dependencies that are lost are those between the first work and > > the setup of the workqueue thread. > > > > And there obviously _should_ not be any dependencies between those. A > > work should not depend on the setup of the thread. > > Furthermore, the save/restore can't preserve those dependencies. The > moment a work exhausts xhlocks[] they are gone. So by assuming the first
They are gone _one time_ only once it has been overwritten, and Recovered at next turn, with original code. But you made it un-recoverable even at the next time and lose all valuable dependencies unconditionally.
> work _will_ exhaust the history there is effectively nothing lost.
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