Date: Sun, 21 Oct 2007 09:43:01 +0200
From: Ingo Molnar <mingo@elte.hu>
To: "Milton D. Miller II" <miltonm@realtime.net>
Cc: Paul Jackson <pj@sgi.com>, Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Fix sched_domain sysctl registration again
Message-ID: <20071021074301.GA14368@elte.hu>
References: <200710201941.l9KJfIGL008482@sullivan.realtime.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <200710201941.l9KJfIGL008482@sullivan.realtime.net>
User-Agent: Mutt/1.5.14 (2007-02-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1805
Lines: 46


* Milton D. Miller II <miltonm@realtime.net> wrote:

> commit 029190c515f15f512ac85de8fc686d4dbd0ae731 (cpuset 
> sched_load_balance flag) was not tested SCHED_DEBUG enabled as 
> committed as it dereferences NULL when used and it reordered the 
> sysctl registration to cause it to never show any domains or their 
> tunables.
> 
> Fixes:
> 
> 1) restore arch_init_sched_domains ordering
> 	we can't walk the domains before we build them
> 
> 	presently we register cpus with empty directories (no domain
> 	directories or files).
> 
> 2) make unregister_sched_domain_sysctl do nothing when already unregistered
> 	detach_destroy_domains is now called one set of cpus at a time
> 	unregister_syctl dereferences NULL if called with a null.
> 
> 	While the the function would always dereference null if called
> 	twice, in the previous code it was always called once and then
> 	was followed a register.  So only the hidden bug of the
> 	sysctl_root_table not being allocated followed by an attempt to
> 	free it would have shown the error.
> 
> 3) always call unregister and register in partition_sched_domains
> 	The code is "smart" about unregistering only needed domains.
> 	Since we aren't guaranteed any calls to unregister, always 
> 	unregister.   Without calling register on the way out we
> 	will not have a table or any sysctl tree.
> 
> 4) warn if register is called without unregistering
> 	The previous table memory is lost, leaving pointers to the
> 	later freed memory in sysctl and leaking the memory of the
> 	tables.

thanks, applied.

	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/