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Date: Thu, 21 Aug 2008 12:18:27 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Ken Chen" <kenchen@google.com>
Cc: linux-kernel@vger.kernel.org, morgan@kernel.org
Subject: Re: [patch] fix NPTL thread iterator construct in cap_set_pg()
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On Fri, 15 Aug 2008 09:24:15 -0700
"Ken Chen" <kenchen@google.com> wrote:

> The usage of while_each_pid_task() construct in cap_set_pg() looks incorrect.
> The macro is meant to form 'do ... while' loop instead of a simple while loop.
> I think currently it will skip thread leader of a NPTL process.
> 
> Fix by convert to 'do ... while' style.
> 
> Signed-off-by: Ken Chen <kenchen@google.com>
> 
> diff --git a/kernel/capability.c b/kernel/capability.c
> index 0101e84..26d8eda 100644
> --- a/kernel/capability.c
> +++ b/kernel/capability.c
> @@ -167,7 +167,7 @@ static inline int cap_set_pg
>  	pgrp = find_vpid(pgrp_nr);
>  	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
>  		target = g;
> -		while_each_thread(g, target) {
> +		do {
>  			if (!security_capset_check(target, effective,
>  						   inheritable, permitted)) {
>  				security_capset_set(target, effective,
> @@ -175,7 +175,7 @@ static inline int cap_set_pg
>  				ret = 0;
>  			}
>  			found = 1;
> -		}
> +		} while_each_thread(g, target);
>  	} while_each_pid_task(pgrp, PIDTYPE_PGID, g);
> 
>  	read_unlock(&tasklist_lock);

cap_set_pg() gets deleted by the credentials patches in linux-next and
afaict nothing replaced it.

Does this patch actually fix anything?  If not, ignoring it would be a
nice labour-saving device...