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From: Oleg Nesterov <oleg@tv-sign.ru>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 01/23] tref: Implement task references.
Date: Tue, 07 Mar 2006 23:38:37 +0300	[thread overview]
Message-ID: <440DEF4D.F3385C28@tv-sign.ru> (raw)
In-Reply-To: m1slpv58yd.fsf@ebiederm.dsl.xmission.com

"Eric W. Biederman" wrote:
> 
> Oleg Nesterov <oleg@tv-sign.ru> writes:
> 
> > I think I have a really good idea.
> >
> > Forget about task ref for a moment. I thinks we can greatly
> > simplify the pids management. We don't PIDTYPE_MAX hash tables,
> > we need only one.
> >
> > The plan:
> >
> >       kill PIDTYPE_TGID
> >       (copy_process/unhash_process need a simple fix)
> 
> Worth doing.  But I think it is an independent problem.

Almost independent, but still we have to do it before we introduce
pid_head. Otherwise next_thread() will be broken, because ->pids[].next
could actually point to pid_head->tasks[].

> pid_head is decent but I am very tempted to call this struct pid.
> Especially if we start getting a lot of pointers to them a simple
> name that makes sense is useful.

Agreed, will rename.

> >       // alloc_pidmap() becomes static,
> >       // do_fork() calls this instead
> >       struct pid_head *alloc_pid(void)
> >       {
>
> Hmm.  I guess that works.  I'm tempted to still return just a pid_t.
> I guess I can't see how the struct pid_head, will be used.

Probably you are right.
 
> There may be another problem here as well.  I don't think we have a lock
> at this point that makes us safe to update the hash table.

Yes,

> If we want to kill the tasklist_lock we also want to add a lock
> to struct pid_head.  Otherwise I don't see how we can safely bump
> the count, above zero.  But using the tasklist_lock for the first
> version shouldn't be a problem.

... and yes. I think we can use pidmap_lock.

Also, find_pid() needs to be rcu safe. I'll try to show the code
tomorrow.

Oleg.

  reply	other threads:[~2006-03-07 20:41 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-23 15:52 [PATCH 00/23] proc cleanup Eric W. Biederman
2006-02-23 15:54 ` [PATCH 01/23] tref: Implement task references Eric W. Biederman
2006-02-23 15:56   ` [PATCH 02/23] proc: Fix the .. inode number on /proc/<pid>/fd Eric W. Biederman
2006-02-23 15:57     ` [PATCH 03/23] proc: Remove useless BKL in proc_pid_readlink Eric W. Biederman
2006-02-23 15:58       ` [PATCH 04/23] proc: Remove unnecessary and misleading assignments from proc_pid_make_inode Eric W. Biederman
2006-02-23 16:00         ` [PATCH 05/23] proc: Simplify the ownership rules for /proc Eric W. Biederman
2006-02-23 16:02           ` Eric W. Biederman
2006-02-23 16:04           ` [PATCH 06/23] proc: Replace proc_inode.type with proc_inode.fd Eric W. Biederman
2006-02-23 16:05             ` [PATCH 07/23] proc: Remove bogus proc_task_permission Eric W. Biederman
2006-02-23 16:06               ` [PATCH 08/23] proc: Kill proc_mem_inode_operations Eric W. Biederman
2006-02-23 16:08                 ` [PATCH 09/23] proc: Properly filter out files that are not visible to a process Eric W. Biederman
2006-02-23 16:10                   ` [PATCH 10/23] proc: Fix the link count for /proc/<pid>/task Eric W. Biederman
2006-02-23 16:12                     ` [PATCH 11/23] proc: Move proc_maps_operations into task_mmu.c Eric W. Biederman
2006-02-23 16:15                       ` [PATCH 12/23] proc: Rewrite the proc dentry flush on exit optimization Eric W. Biederman
2006-02-23 16:16                         ` [PATCH 13/23] proc: Close the race of a process dying durning lookup Eric W. Biederman
2006-02-23 16:18                           ` [PATCH 14/23] proc: Make PROC_NUMBUF the buffer size for holding a integers as strings Eric W. Biederman
2006-02-23 16:20                             ` [PATCH 15/23] proc: refactor reading directories of tasks Eric W. Biederman
2006-02-23 16:23                               ` [PATCH 16/23] proc: Don't lock task_structs indefinitely Eric W. Biederman
2006-02-23 16:24                                 ` [PATCH 17/23] proc: Give the root directory a task Eric W. Biederman
2006-02-23 16:25                                   ` [PATCH 18/23] proc: Reorder the functions in base.c Eric W. Biederman
2006-02-23 16:27                                     ` [PATCH 19/23] proc: Modify proc_pident_lookup to be completely table driven Eric W. Biederman
2006-02-23 16:28                                       ` [PATCH 20/23] proc: Make the generation of the self symlink " Eric W. Biederman
2006-02-23 16:30                                         ` [PATCH 21/23] proc: Factor out an instantiate method from every lookup method Eric W. Biederman
2006-02-23 16:32                                           ` [PATCH 22/23] proc: Remove the hard coded inode numbers Eric W. Biederman
2006-02-23 16:34                                             ` [PATCH 23/23] proc: Merge proc_tid_attr and proc_tgid_attr Eric W. Biederman
2006-02-23 16:49   ` [PATCH 01/23] tref: Implement task references Eric W. Biederman
2006-03-02 19:16     ` Oleg Nesterov
2006-03-02 20:37       ` Oleg Nesterov
2006-03-02 22:19       ` Eric W. Biederman
2006-03-03 16:56         ` Oleg Nesterov
2006-03-03 17:48           ` Eric W. Biederman
2006-03-04 11:16           ` Eric W. Biederman
2006-03-04 12:31             ` Oleg Nesterov
2006-03-04 17:30               ` Oleg Nesterov
2006-03-06 21:06         ` Oleg Nesterov
2006-03-06 22:18           ` Eric W. Biederman
2006-03-07 20:44             ` Oleg Nesterov
2006-03-07  1:39           ` Eric W. Biederman
2006-03-07 20:38             ` Oleg Nesterov [this message]
2006-03-07 13:12           ` Eric W. Biederman
2006-03-07 21:02             ` Oleg Nesterov
2006-03-07 23:00               ` Eric W. Biederman
2006-03-03 19:23     ` Oleg Nesterov
2006-03-04 10:51       ` Eric W. Biederman
2006-02-25 12:27 ` [PATCH 00/23] proc cleanup Andrew Morton
2006-02-25 13:34   ` Eric W. Biederman
2006-02-25 15:20   ` Eric W. Biederman
2006-02-27 15:26 ` Serge E. Hallyn
2006-02-27 15:56   ` Eric W. Biederman

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