linux-kernel - Re: [PATCH tip/core/rcu 08/10] rcu: Add a TINY_PREEMPT

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Tue, 17 Aug 2010 17:36:13 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	paulmck@...ux.vnet.ibm.com
CC:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	linux-kernel@...r.kernel.org, mingo@...e.hu, dipankar@...ibm.com,
	akpm@...ux-foundation.org, josh@...htriplett.org,
	dvhltc@...ibm.com, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, eric.dumazet@...il.com
Subject: Re: [PATCH tip/core/rcu 08/10] rcu: Add a TINY_PREEMPT_RCU

On 08/17/2010 06:24 AM, Paul E. McKenney wrote:

>> --(t->rcu_read_lock_nesting)
>>
>> could be split in two distinct operations:
>>
>> read t->rcu_read_lock_nesting
>> decrement t->rcu_read_lock_nesting
>>
>> Note that in order to know the result required to pass the sequence
>> point "&&" (the test), we only need to perform the read, not the
>> decrement. AFAIU, gcc would be in its rights to move the
>> t->rcu_read_lock_nesting update after the volatile access.
> 
> I will run this by some compiler experts.
> 

We can just use "read and decrement statements" instead of "--" to
avoid dependency from compilers.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/