lkml.org 
[lkml]   [2020]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH memory-model 5/8] tools/memory-model: Add a glossary of LKMM terms
On Thu, Nov 05, 2020 at 02:00:14PM -0800, paulmck@kernel.org wrote:
> From: "Paul E. McKenney" <paulmck@kernel.org>
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> tools/memory-model/Documentation/glossary.txt | 155 ++++++++++++++++++++++++++
> 1 file changed, 155 insertions(+)
> create mode 100644 tools/memory-model/Documentation/glossary.txt
>
> diff --git a/tools/memory-model/Documentation/glossary.txt b/tools/memory-model/Documentation/glossary.txt
> new file mode 100644
> index 0000000..036fa28
> --- /dev/null
> +++ b/tools/memory-model/Documentation/glossary.txt
> @@ -0,0 +1,155 @@
> +This document contains brief definitions of LKMM-related terms. Like most
> +glossaries, it is not intended to be read front to back (except perhaps
> +as a way of confirming a diagnosis of OCD), but rather to be searched
> +for specific terms.
> +
> +
> +Address Dependency: When the address of a later memory access is computed
> + based on the value returned by an earlier load, an "address
> + dependency" extends from that load extending to the later access.
> + Address dependencies are quite common in RCU read-side critical
> + sections:
> +
> + 1 rcu_read_lock();
> + 2 p = rcu_dereference(gp);
> + 3 do_something(p->a);
> + 4 rcu_read_unlock();
> +
> + In this case, because the address of "p->a" on line 3 is computed
> + from the value returned by the rcu_dereference() on line 2, the
> + address dependency extends from that rcu_dereference() to that
> + "p->a". In rare cases, optimizing compilers can destroy address
> + dependencies. Please see Documentation/RCU/rcu_dereference.txt
> + for more information.
> +
> + See also "Control Dependency".

There should also be an entry for "Data Dependency", linked from here
and from Control Dependency.

> +Marked Access: An access to a variable that uses an special function or
> + macro such as "r1 = READ_ONCE()" or "smp_store_release(&a, 1)".

How about "r1 = READ_ONCE(x)"?

Alan

\
 
 \ /
  Last update: 2020-11-06 18:00    [W:0.139 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site