linux-kernel - Re: [PATCH] lktdm: Bring support for hardlockup, softlockup and hung task crashes

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:	Sun, 16 May 2010 12:35:08 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Simon Kagstrom <simon.kagstrom@...insight.net>,
	Ingo Molnar <mingo@...e.hu>, Don Zickus <dzickus@...hat.com>
Subject: Re: [PATCH] lktdm: Bring support for hardlockup, softlockup and
	hung task crashes

On Sun, May 16, 2010 at 01:36:36PM +0400, Cyrill Gorcunov wrote:
> On Sun, May 16, 2010 at 07:39:51AM +0200, Frederic Weisbecker wrote:
> ...  
> >  static struct jprobe lkdtm;
> > @@ -320,6 +326,20 @@ static void lkdtm_do_action(enum ctype which)
> >  		memset(data, 0x78, len);
> >  		break;
> >  	}
> > +	case SOFTLOCKUP:
> > +		preempt_disable();
> > +		for (;;)
> > +			cpu_relax();
> > +		break;
> > +	case HARDLOCKUP:
> > +		local_irq_disable();
> > +		for (;;)
> > +			cpu_relax();
> > +		break;
> > +	case HUNG_TASK:
> > +		set_current_state(TASK_UNINTERRUPTIBLE);
> > +		schedule();
> > +		break;
> >  	case NONE:
> >  	default:
> >  		break;
> 
> Looks good to me. Btw perhaps we may simplify it a bit:
> 
> 	case HARDLOCKUP:
> 		local_irq_disable();
> 	case SOFTLOCKUP:
> 		preempt_disable();
> 		for (;;)
> 			cpu_relax();
> 		break;
> 
> since it'll save a few bytes. What do you think? Did I miss
> something?


It would make the code a bit less clear in that people
might stick on the reason to disable preemption after disabling
irq, especially with a code that already does something rather
unusual ;)

--
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/