From: "H. Peter Anvin" <hpa@kernel.org>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: tj@kernel.org, fuse-devel@lists.sourceforge.net, greg@kroah.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/7] FUSE: implement ioctl support
Date: Thu, 28 Aug 2008 14:27:26 -0700 [thread overview]
Message-ID: <48B7183E.3010100@kernel.org> (raw)
In-Reply-To: <E1KYoX9-0004Mn-NX@pomaz-ex.szeredi.hu>
Miklos Szeredi wrote:
> On Thu, 28 Aug 2008, H. Peter Anvin wrote:
>> This is *hard* to get right, and we screw this up in the kernel with
>> painful regularity. The throught of having user-space processes, which
>> don't have access to the kernel locking primitives and functions like
>> copy_from_user() dealing with this stuff scares me crazy.
>
> What issues exactly are you thinking of?
Memory changing underneath you. It can be dealt with by very careful
sequencing only.
>> That is why I'm suggesting using an in-kernel linearizer.
>
> Lots of complexity, ugh... Even Tejun's current scheme is better IMO.
And then you get *no* privilege separation, for one thing, so why even
bother doing it in userspace?
-hpa
next prev parent reply other threads:[~2008-08-28 21:27 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-28 17:40 [PATCHSET] FUSE: extend FUSE to support more operations Tejun Heo
2008-08-28 17:40 ` [PATCH 1/7] FUSE: add include protectors Tejun Heo
2008-08-28 17:40 ` [PATCH 2/7] FUSE: pass nonblock flag to client Tejun Heo
2008-08-28 17:40 ` [PATCH 3/7] FUSE: implement nonseekable open Tejun Heo
2008-08-28 17:41 ` [PATCH 4/7] FUSE: implement direct lseek support Tejun Heo
2008-08-28 17:41 ` [PATCH 5/7] FUSE: implement ioctl support Tejun Heo
2008-08-28 17:51 ` Greg KH
2008-08-28 17:59 ` Tejun Heo
2008-08-28 18:01 ` Tejun Heo
2008-08-28 18:13 ` Miklos Szeredi
2008-08-28 18:17 ` Tejun Heo
2008-08-28 18:23 ` Miklos Szeredi
2008-08-28 18:34 ` Tejun Heo
2008-08-28 19:25 ` Miklos Szeredi
2008-08-28 19:42 ` Tejun Heo
2008-08-28 20:02 ` Miklos Szeredi
2008-08-29 2:19 ` Tejun Heo
2008-08-29 7:59 ` Miklos Szeredi
2008-08-29 8:12 ` Tejun Heo
2008-08-29 8:29 ` Miklos Szeredi
2008-08-29 9:03 ` Tejun Heo
2008-08-29 19:17 ` Eric W. Biederman
2008-08-29 19:47 ` Arnd Bergmann
2008-08-30 11:40 ` Tejun Heo
2008-09-01 11:57 ` Miklos Szeredi
2008-09-01 12:03 ` Tejun Heo
2008-09-03 14:32 ` Eric W. Biederman
2008-09-03 14:40 ` Tejun Heo
2008-09-03 21:51 ` Eric W. Biederman
2008-09-04 0:09 ` Tejun Heo
2008-08-29 11:31 ` [fuse-devel] " Roger Willcocks
2008-08-29 11:54 ` Tejun Heo
2008-08-28 20:48 ` Alan Cox
2008-08-28 18:02 ` Tejun Heo
2008-08-28 18:14 ` Greg KH
2008-08-28 18:25 ` Tejun Heo
2008-08-28 18:20 ` H. Peter Anvin
2008-08-28 18:28 ` Tejun Heo
2008-08-28 19:08 ` H. Peter Anvin
2008-08-28 19:18 ` Miklos Szeredi
2008-08-28 20:21 ` H. Peter Anvin
2008-08-28 20:55 ` Miklos Szeredi
2008-08-28 21:27 ` H. Peter Anvin [this message]
2008-08-29 7:32 ` Miklos Szeredi
2008-08-28 17:41 ` [PATCH 6/7] FUSE: implement unsolicited notification Tejun Heo
2008-08-28 17:41 ` [PATCH 7/7] FUSE: implement poll support Tejun Heo
2008-08-28 18:20 ` [PATCHSET] FUSE: extend FUSE to support more operations Miklos Szeredi
2008-08-28 18:23 ` Tejun Heo
2008-10-14 8:21 ` Tejun Heo
2008-10-14 9:37 ` Miklos Szeredi
2008-10-14 12:16 ` [fuse-devel] " Szabolcs Szakacsits
2008-10-14 12:43 ` Miklos Szeredi
[not found] ` <2cff7cb50810141032m5793a405h7425dfa122fb67ba@mail.gmail.com>
2008-10-14 21:04 ` Miklos Szeredi
2008-11-12 8:41 ` Tejun Heo
2008-11-12 9:14 ` Christoph Hellwig
2008-11-12 9:30 ` Tejun Heo
2008-11-12 9:36 ` Miklos Szeredi
2008-11-12 9:43 ` [fuse-devel] " Mike Hommey
2008-11-12 10:00 ` Miklos Szeredi
2008-11-13 5:54 ` Tejun Heo
2008-11-13 6:06 ` Tejun Heo
2008-11-13 11:19 ` Miklos Szeredi
2008-11-13 11:29 ` Tejun Heo
2008-11-13 11:57 ` Miklos Szeredi
2008-11-13 12:14 ` Tejun Heo
2008-11-13 6:26 ` Tejun Heo
2008-11-13 11:47 ` Miklos Szeredi
2008-11-13 11:54 ` Tejun Heo
2008-11-13 11:58 ` Miklos Szeredi
2008-11-13 12:34 ` Miklos Szeredi
2008-11-13 13:23 ` Tejun Heo
2008-11-13 13:42 ` Miklos Szeredi
2008-11-13 14:29 ` Tejun Heo
2008-11-13 14:48 ` Miklos Szeredi
2008-11-13 15:10 ` Tejun Heo
2008-11-13 15:52 ` Miklos Szeredi
2008-11-13 16:00 ` Tejun Heo
2008-11-17 9:17 ` Tejun Heo
2008-11-17 10:16 ` [fuse-devel] " Miklos Szeredi
2008-11-18 3:32 ` Tejun Heo
2008-11-18 9:33 ` Miklos Szeredi
2008-11-18 10:30 ` Tejun Heo
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