linux-kernel - Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory barrier (v5)

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, 19 Jan 2010 14:43:44 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	akpm@...ux-foundation.org, josh@...htriplett.org,
	tglx@...utronix.de, Valdis.Kletnieks@...edu, dhowells@...hat.com,
	laijs@...fujitsu.com, dipankar@...ibm.com
Subject: Re: [RFC PATCH] introduce sys_membarrier(): process-wide memory
 barrier (v5)

On Tue, 2010-01-19 at 19:37 +0100, Peter Zijlstra wrote:

> So about that [*], Oleg, kernel/signal.c:SYSCALL_DEFINE0(pause) does:
> 
> SYSCALL_DEFINE0(pause)
> {
>         current->state = TASK_INTERRUPTIBLE;
>         schedule();
>         return -ERESTARTNOHAND;
> }
> 
> Isn't that ->state assignment buggy? If so, there appear to be quite a
> few such sites, which worries me.
> 

That looks buggy to me. Isn't this the reason we have
set_current_state()?

Although, since it is not checking any condition, it may not be buggy.
The check inside scheduler for state != TASK_RUNNING is protected inside
the rq locks, and any other task must grab the rq lock of the task
before it can change the task's state. schedule() also checks for
signals which would force schedule() to wake it up.

But that said, I still think that should be changed to
set_current_state(TASK_INTERRUPTIBLE).
	

-- Steve



--
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/