lkml.org 
[lkml]   [2018]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC LKMM 1/7] tools/memory-model: Add extra ordering for locks and remove it for ordinary release/acquire
> > Yes, it's true that implementing locks with atomic_cmpxchg_acquire 
> > should be correct on all existing architectures. And Paul has invited
> > a patch to modify the LKMM accordingly. If you feel that such a change
> > would be a useful enhancement to the LKMM's applicability, please write
> > it.
>
> Yes, please! That would be the "RmW" discussion which Andrea partially
> quoted earlier on, so getting that going independently from this patch
> sounds like a great idea to me.

That was indeed one of the proposal we discussed. As you recalled, that
proposal only covered RmWs load-acquire (and ordinary store-release); in
particular, I realized that comments such as:

"The atomic_cond_read_acquire() call above has provided the
necessary acquire semantics required for locking."

[from kernel/locking/qspinlock.c]

(for example) would still _not have "generic validity" _if we added the
above po-unlock-rf-lock-po term... (which, again, makes me somehow uncon-
fortable); Would to have _all_ the acquire be admissible for you?

Andrea


>
> Cheers,
>
> Will

\
 
 \ /
  Last update: 2018-08-31 20:33    [W:0.117 / U:0.524 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site