Messages in this thread | | | Date | Mon, 29 Nov 2010 17:43:29 +0100 | From | Oleg Nesterov <> | Subject | Re: [patch 4/4] taskstats: Export "cdata_acct" with taskstats |
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On 11/25, Michael Holzheu wrote: > > Hello Oleg, > > On Thu, 2010-11-25 at 14:26 +0100, Oleg Nesterov wrote: > > On 11/19, Michael Holzheu wrote: > > > > > > From: Michael Holzheu <holzheu@linux.vnet.ibm.com> > > > > > > With this patch the (full) cumulative CPU time is added to "struct taskstats". > > > The CPU time is only returned for the thread group leader. > > > > > > ... > > > > > > + if (tsk->tgid == tsk->pid > > > > thread_group_leader() ? > > Yes, that's better. > > > > && lock_task_sighand(tsk, &flags)) { > > > > Do you really need ->siglock? Starting from 2.6.35 it is always > > safe to access ->signal. > > Hmmm, if you say that... > > I just did it like it is done in e.g. fs/proc/base.c (proc_pid_limits). > Can we remove the locking there, too?
We can certainly remove more siglock's which were previously needed to access ->signal.
This particular one is just wrong. We need task_lock(group_leader) to read signal->rlim atomically. However, it is not trivial to do this correctly. Probably we should ignore this minor problem.
In any case, this ->siglock buys nothing today.
Oleg.
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