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From: Christoph Hellwig <hch@lst.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-rtc@vger.kernel.org,
	Alessandro Zummo <a.zummo@towertech.it>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	devel@driverdev.osuosl.org, linux-afs@lists.infradead.org,
	linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org,
	jfs-discussion@lists.sourceforge.net,
	Christoph Hellwig <hch@lst.de>,
	linux-acpi@vger.kernel.org, netdev@vger.kernel.org,
	netfilter-devel@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Jiri Slaby <jslaby@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-ext4@vger.kernel.org, Alexey Dobriyan <adobriyan@gmail.com>,
	megaraidlinux.pdl@broadcom.com, drbd-dev@lists.linbit.com
Subject: Re: [PATCH 11/40] ipv6/flowlabel: simplify pid namespace lookup
Date: Tue, 15 May 2018 16:56:43 +0200	[thread overview]
Message-ID: <20180515145643.GA661@lst.de> (raw)
In-Reply-To: <878t8y46sy.fsf@xmission.com>

On Sat, May 05, 2018 at 07:37:33AM -0500, Eric W. Biederman wrote:
> Christoph Hellwig <hch@lst.de> writes:
> 
> > The shole seq_file sequence already operates under a single RCU lock pair,
> > so move the pid namespace lookup into it, and stop grabbing a reference
> > and remove all kinds of boilerplate code.
> 
> This is wrong.
> 
> Move task_active_pid_ns(current) from open to seq_start actually means
> that the results if you pass this proc file between callers the results
> will change.  So this breaks file descriptor passing.
> 
> Open is a bad place to access current.  In the middle of read/write is
> broken.
> 
> 
> In this particular instance looking up the pid namespace with
> task_active_pid_ns was a personal brain fart.  What the code should be
> doing (with an appropriate helper) is:
> 
> struct pid_namespace *pid_ns = inode->i_sb->s_fs_info;
> 
> Because each mount of proc is bound to a pid namespace.  Looking up the
> pid namespace from the super_block is a much better way to go.

What do you have in mind for the helper?  For now I've thrown it in
opencoded into my working tree, but I'd be glad to add a helper.

struct pid_namespace *proc_pid_namespace(struct inode *inode)
{
	// maybe warn on for s_magic not on procfs??
	return inode->i_sb->s_fs_info;
}

?
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  reply	other threads:[~2018-05-15 14:56 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25 15:47 simplify procfs code for seq_file instances V2 Christoph Hellwig
2018-04-25 15:47 ` [PATCH 01/40] net/can: single_open_net needs to be paired with single_release_net Christoph Hellwig
2018-04-25 15:47 ` [PATCH 02/40] proc: simplify proc_register calling conventions Christoph Hellwig
2018-04-25 15:47 ` [PATCH 03/40] proc: add a proc_create_reg helper Christoph Hellwig
2018-04-25 15:47 ` [PATCH 04/40] proc: introduce proc_create_seq{,_data} Christoph Hellwig
2018-04-25 15:47 ` [PATCH 05/40] proc: introduce proc_create_seq_private Christoph Hellwig
2018-04-25 15:47 ` [PATCH 06/40] proc: introduce proc_create_single{,_data} Christoph Hellwig
2018-04-26  1:45   ` Finn Thain
2018-05-15 13:58     ` Christoph Hellwig
2018-04-25 15:47 ` [PATCH 07/40] ipv{4,6}/udp{,lite}: simplify proc registration Christoph Hellwig
2018-04-25 15:47 ` [PATCH 08/40] ipv{4,6}/tcp: simplify procfs registration Christoph Hellwig
2018-04-25 15:47 ` [PATCH 09/40] ipv{4,6}/ping: simplify proc file creation Christoph Hellwig
2018-04-25 15:47 ` [PATCH 10/40] ipv{4, 6}/raw: simplify ѕeq_file code Christoph Hellwig
2018-04-25 15:47 ` [PATCH 11/40] ipv6/flowlabel: simplify pid namespace lookup Christoph Hellwig
2018-05-05 12:37   ` Eric W. Biederman
2018-05-15 14:56     ` Christoph Hellwig [this message]
2018-05-17  5:28       ` Eric W. Biederman
2018-05-17  6:42         ` Christoph Hellwig
2018-05-17 19:14           ` Eric W. Biederman
2018-04-25 15:47 ` [PATCH 12/40] net/kcm: simplify proc registration Christoph Hellwig
2018-04-25 15:48 ` [PATCH 13/40] netfilter/x_tables: simplify ѕeq_file code Christoph Hellwig
2018-04-25 15:48 ` [PATCH 14/40] net: move seq_file_single_net to <linux/seq_file_net.h> Christoph Hellwig
2018-04-25 15:48 ` [PATCH 15/40] proc: introduce proc_create_net{,_data} Christoph Hellwig
2018-04-25 15:48 ` [PATCH 16/40] proc: introduce proc_create_net_single Christoph Hellwig
2018-04-25 15:48 ` [PATCH 17/40] acpi/battery: simplify procfs code Christoph Hellwig
2018-04-25 15:48 ` [PATCH 18/40] sgi-gru: " Christoph Hellwig
2018-04-25 15:48 ` [PATCH 19/40] megaraid: " Christoph Hellwig
2018-04-25 15:48 ` [PATCH 20/40] sg: " Christoph Hellwig
2018-04-25 15:48 ` [PATCH 21/40] afs: " Christoph Hellwig
2018-04-30 23:20   ` [PATCH 0/3] afs: Network-namespacing and proc David Howells
2018-04-30 23:20     ` [PATCH 1/3] afs: Rearrange fs/afs/proc.c David Howells
2018-05-15 13:43       ` Christoph Hellwig
2018-04-30 23:20     ` [PATCH 2/3] proc: Add a way to make network proc files writable David Howells
2018-05-15 13:48       ` Christoph Hellwig
2018-05-15 14:16       ` David Howells
2018-04-30 23:20     ` [PATCH 3/3] afs: Implement namespacing David Howells
2018-05-15 13:53       ` Christoph Hellwig
2018-05-15 14:28       ` 'Adding' a writable proc file under /proc/net/afs/ [was [PATCH 3/3] afs: Implement namespacing] David Howells
2018-04-25 15:48 ` [PATCH 22/40] ext4: simplify procfs code Christoph Hellwig
2018-04-25 15:48 ` [PATCH 23/40] jfs: " Christoph Hellwig
2018-04-25 15:48 ` [PATCH 24/40] staging/rtl8192u: " Christoph Hellwig
2018-04-25 15:48 ` [PATCH 25/40] resource: switch to proc_create_seq_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 26/40] drbd: switch to proc_create_single Christoph Hellwig
2018-04-25 15:48 ` [PATCH 27/40] rtc/proc: switch to proc_create_single_data Christoph Hellwig
2018-04-25 18:25   ` Alexandre Belloni
2018-04-25 15:48 ` [PATCH 28/40] bonding: switch to proc_create_seq_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 29/40] hostap: switch to proc_create_{seq,single}_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 30/40] neigh: switch to proc_create_seq_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 31/40] netfilter/xt_hashlimit: switch to proc_create_{seq, single}_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 32/40] netfilter/x_tables: switch to proc_create_seq_private Christoph Hellwig
2018-04-25 15:48 ` [PATCH 33/40] bluetooth: switch to proc_create_seq_data Christoph Hellwig
2018-04-25 15:48 ` [PATCH 34/40] atm: simplify procfs code Christoph Hellwig
2018-05-05 12:51   ` Eric W. Biederman
2018-05-15 14:12     ` Christoph Hellwig
2018-05-17  1:15       ` Eric W. Biederman
2018-04-25 15:48 ` [PATCH 35/40] atm: switch to proc_create_seq_private Christoph Hellwig
2018-04-25 15:48 ` [PATCH 36/40] isdn: replace ->proc_fops with ->proc_show Christoph Hellwig
2018-04-25 15:48 ` [PATCH 37/40] proc: don't detour through seq->private to get the inode Christoph Hellwig
2018-04-25 15:48 ` [PATCH 38/40] ide: remove ide_driver_proc_write Christoph Hellwig
2018-05-05 13:09   ` Eric W. Biederman
2018-04-25 15:48 ` [PATCH 39/40] ide: replace ->proc_fops with ->proc_show Christoph Hellwig
2018-04-25 15:48 ` [PATCH 40/40] tty: " Christoph Hellwig
2018-04-30 13:19 ` [PATCH 04/40] proc: introduce proc_create_seq{,_data} David Howells
2018-05-15 14:42   ` Christoph Hellwig
2018-04-30 15:38 ` simplify procfs code for seq_file instances V2 David Howells
2018-05-06 17:19 ` Alexey Dobriyan
2018-05-06 17:45   ` Al Viro
2018-05-09 16:53     ` Alexey Dobriyan
2018-05-15 14:03   ` Christoph Hellwig

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