Re: [PATCH tip/core/rcu 01/13] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU

[Paul E. McKenney]

On Fri, Apr 14, 2017 at 10:45:44AM +0200, Peter Zijlstra wrote:
> On Thu, Apr 13, 2017 at 02:30:19PM -0700, Eric Dumazet wrote:
> > On Thu, Apr 13, 2017 at 9:17 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > 
> > > git log -S SLAB_DESTROY_BY_RCU
> > 
> > Maybe, but "git log -S" is damn slow at least here.
> > 
> > While "git grep" is _very_ fast
> 
> All true. But in general we don't leave endless markers around like
> this.
> 
> For instance:
> 
>   /* the function formerly known as smp_mb__before_clear_bit() */
> 
> is not part of the kernel tree. People that used that thing out of tree
> get to deal with it in whatever way they see fit.

Sometimes we don't provide markers and sometimes we do:

$ git grep synchronize_kernel
Documentation/RCU/RTFP.txt:,Title="API change: synchronize_kernel() deprecated"
Documentation/RCU/RTFP.txt:     Jon Corbet describes deprecation of synchronize_kernel()
kernel/rcu/tree.c: * synchronize_kernel() API.  In contrast, synchronize_rcu() only

Given that it has been more than a decade, I could easily see my way to
removing this synchronize_kernel() tombstone in kernel/rcu/tree.c if
people are annoyed by it.  But thus far, no one has complained.

So how long should we wait to remove the SLAB_DESTROY_BY_RCU tombstone?
I can easily add an event to my calendar to remind me to remove it.

							Thanx, Paul