To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: miklos@szeredi.hu, miklos@szeredi.hu, luto@mit.edu,
       akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
       linux-kernel@vger.kernel.org
In-reply-to: <20091207122346.6d18a8e1@lxorguk.ukuu.org.uk> (message from Alan
	Cox on Mon, 7 Dec 2009 12:23:46 +0000)
Subject: Re: [PATCH v3] vfs: new O_NODE open flag
References: <E1NFrsv-0000mE-2L@pomaz-ex.szeredi.hu>
	<20091202191549.1dbffa2e@lxorguk.ukuu.org.uk>
	<E1NFva6-0001AI-0J@pomaz-ex.szeredi.hu>
	<20091202204828.4fa0c108@lxorguk.ukuu.org.uk>
	<E1NG4WJ-00026r-GE@pomaz-ex.szeredi.hu>
	<4B1A7159.3070101@mit.edu>
	<E1NH0Ub-0007oy-43@pomaz-ex.szeredi.hu>
	<20091205202838.3456b6fc@lxorguk.ukuu.org.uk>
	<E1NH1MB-0007v8-Ps@pomaz-ex.szeredi.hu>
	<20091205231304.03a4af61@lxorguk.ukuu.org.uk>
	<E1NHWlu-00029N-1t@pomaz-ex.szeredi.hu> <20091207122346.6d18a8e1@lxorguk.ukuu.org.uk>
Message-Id: <E1NHctp-00032C-A1@pomaz-ex.szeredi.hu>
From: Miklos Szeredi <miklos@szeredi.hu>
Date: Mon, 07 Dec 2009 13:41:09 +0100
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 880
Lines: 23

On Mon, 7 Dec 2009, Alan Cox wrote:
> The standard udev unload is a true open barrier so has an implicit
> revoke() caused by the fact you cannot keep a handle to the filename open
> during the udev sequence (or the old driver would be pinned by a refcount
> and not unload).

True, udev unload is an open barrier (modulo races), but O_NODE opens
simply don't matter in this respect, because they don't have anything
to do with the driver.

  ln /dev/foo /dev/shm/my_secret_device_link
  (foo is removed)
  open("/dev/shm/my_secret_device_link", O_RDWR)

How is this different than keeping the device open with O_NODE?

Thanks,
Miklos
--
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/