linux-kernel - Re: [RELEASE] Userspace RCU 0.15.0

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87ed21hupb.fsf@laura>
Date: Sat, 21 Dec 2024 11:22:40 -0500
From: Olivier Dion <odion@...icios.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 linux-kernel@...r.kernel.org, lttng-dev@...ts.lttng.org
Cc: Ondřej Surý <ondrej@....org>, paulmck
 <paulmck@...nel.org>, Alan Stern
 <stern@...land.harvard.edu>, Lai Jiangshan <jiangshanlai@...il.com>, Brad
 Smith <brad@...style.com>, lwn@....net
Subject: Re: [RELEASE] Userspace RCU 0.15.0

On Fri, 20 Dec 2024, Mathieu Desnoyers <mathieu.desnoyers@...icios.com> wrote:
> Hi,
[...]
>    * Introduction of the CMM memory model with the following new primitives:
>      
>        - uatomic_load(addr, memory_order)
>      
>        - uatomic_store(addr, value, memory_order)
>        - uatomic_and_mo(addr, mask, memory_order)
>        - uatomic_or_mo(addr, mask, memory_order)
>        - uatomic_add_mo(addr, value, memory_order)
>        - uatomic_sub_mo(addr, value, memory_order)
>        - uatomic_inc_mo(addr, memory_order)
>        - uatomic_dec_mo(addr, memory_order)
>      
>        - uatomic_add_return_mo(addr, value, memory_order)
>        - uatomic_sub_return_mo(addr, value, memory_order)
>      
>        - uatomic_xchg_mo(addr, value, memory_order)
>      
>        - uatomic_cmpxchg_mo(addr, old, new,
>                             memory_order_success,
>                             memory_order_failure)
>
> The uatomic API was extended to support explicit memory ordering.
> For instance, the previous uatomic_cmpxchg() now has a
> uatomic_cmpxchg_mo() counterpart, which takes a memory ordering
> argument.

It is worth mentioning that the `*_mo' variants are not public API.
Instead, the current uatomic API is extended by adding an optional
memory odring parameter for the various atomic operation.

For example, uatomic_xchg(addr, value) is equivalent to
uatomic_xchg(addr, value, CMM_SEQ_CST_FENCE).  But user can choose a
different memory ordering.  For example: uatomix_xchg(addr, value,
CMM_RELEASE).

[...]

Thanks,
Olivier
-- 
Olivier Dion
EfficiOS Inc.
https://www.efficios.com