From: Rusty Russell <rusty@rustcorp.com.au>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: akpm@zip.com.au, linux-kernel@vger.kernel.org
Subject: Re: [patch 6/12] hold atomic kmaps across generic_file_read
Date: Mon, 12 Aug 2002 17:45:30 +1000 [thread overview]
Message-ID: <20020812174530.398156a1.rusty@rustcorp.com.au> (raw)
In-Reply-To: <Pine.LNX.4.44.0208091813470.1165-100000@home.transmeta.com>
On Fri, 9 Aug 2002 18:33:09 -0700 (PDT)
Linus Torvalds <torvalds@transmeta.com> wrote:
> repeat:
> kmap_atomic(..); // this increments preempt count
> nr = copy_from_user(..);
Please please please use a different name for "I know I'm not preemptible but
I can handle it" or a flag or something.
That leaves us with the possibility of a BUG() in the "normal" copy_to/from_user
for all those "I'm holding a spinlock while copying to userspace wheeee!" bugs.
Very common mistake for new kernel authors.
With the preempt count we have an easy way of detecting this at runtime: I'd
like to keep that.
Rusty.
--
there are those who do and those who hang on and you don't see too
many doers quoting their contemporaries. -- Larry McVoy
next prev parent reply other threads:[~2002-08-12 8:17 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-10 0:57 [patch 6/12] hold atomic kmaps across generic_file_read Andrew Morton
2002-08-10 1:33 ` Linus Torvalds
2002-08-10 3:53 ` Andrew Morton
2002-08-10 3:53 ` Linus Torvalds
2002-08-10 6:12 ` Andrew Morton
2002-08-10 7:25 ` Linus Torvalds
2002-08-10 9:08 ` Andrew Morton
2002-08-10 12:44 ` Daniel Phillips
2002-08-10 17:01 ` Linus Torvalds
2002-08-10 18:16 ` Daniel Phillips
2002-08-10 18:32 ` Linus Torvalds
2002-08-10 18:46 ` Daniel Phillips
2002-08-10 14:16 ` Rik van Riel
2002-08-10 17:03 ` Linus Torvalds
2002-08-10 17:36 ` Jamie Lokier
2002-08-10 17:46 ` Linus Torvalds
2002-08-10 17:55 ` Jamie Lokier
2002-08-10 18:42 ` Linus Torvalds
2002-08-10 18:52 ` Jeff Garzik
2002-08-10 19:01 ` Christoph Hellwig
2002-08-10 19:04 ` Jeff Garzik
2002-08-12 15:20 ` Ingo Oeser
2002-08-12 0:18 ` Albert D. Cahalan
2002-08-12 14:11 ` Jeff Garzik
2002-08-12 14:46 ` David Woodhouse
2002-08-10 19:10 ` Jamie Lokier
2002-08-10 22:42 ` Linus Torvalds
2002-08-11 3:17 ` Simon Kirby
2002-08-11 6:07 ` Andrew Morton
2002-08-11 8:46 ` Simon Kirby
2002-08-11 9:36 ` Andrew Morton
2002-08-11 9:49 ` Andrew Morton
2002-08-11 10:28 ` Andrew Morton
2002-08-11 18:52 ` Linus Torvalds
2002-08-12 3:28 ` Andrew Morton
2002-08-12 3:27 ` Linus Torvalds
2002-08-12 4:08 ` Andrew Morton
2002-08-12 6:20 ` Simon Kirby
2002-08-12 6:44 ` Andrew Morton
2002-08-12 19:43 ` Trond Myklebust
2002-08-12 20:43 ` Andrew Morton
2002-08-11 8:00 ` Daniel Phillips
2002-08-11 19:00 ` Linus Torvalds
2002-08-11 19:43 ` Daniel Phillips
2002-08-11 0:34 ` Andrew Morton
2002-08-11 0:56 ` Linus Torvalds
2002-08-11 1:27 ` Andrew Morton
2002-08-12 7:45 ` Rusty Russell [this message]
2002-08-12 9:45 ` Daniel Phillips
2002-08-12 20:29 ` Linus Torvalds
2002-08-12 21:21 ` Daniel Phillips
2002-08-12 17:30 ` Linus Torvalds
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