linux-kernel - Re: [PATCH v2 0/5] [RFC] copy_strtok_from

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Message-ID: <20090226123017.GA2041@elte.hu>
Date:	Thu, 26 Feb 2009 13:30:17 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 0/5] [RFC] copy_strtok_from_user

* Ingo Molnar <mingo@...e.hu> wrote:

> 
> * Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > On Thu, 2009-02-26 at 00:32 -0500, Steven Rostedt wrote:
> > > This is the second series of the uaccess code.
> > > 
> > > Changes in v2:
> > > 
> > >  - moved probe_kernel_* functions to lib/uaccess.c
> > > 
> > >  - renamed copy_word_from_user to copy_strtok_from_user.
> > > 
> > >  - changed copy_strtok_from_user to pass in a delimiter string.
> > >    ftrace defines SPACE to be ' \t\r\n'.
> > > 
> > > Ingo,
> > > I added your copy right to lib/uaccess.c since git blame shows you
> > > as the author of the probe_kernel_* code. Also, is it OK that I
> > > added the "GPL v2" line in that file as well?
> > > 
> > > Andrew,
> > > Since you are, in essence, the memory maintainer, could you give
> > > your Acked-by: to the copy_strtok_from_user code.
> > > 
> > > The probe_kernel code is still EXPORT_SYMBOL_GPL, and I added
> > > that too to copy_strtok_from_user. Are there any objections to that?
> > 
> > I have to ask,..
> > 
> > cant this be done with a regular copy_from_user() followed 
> > by a regular strtok()? Do we really have to combine all 
> > that?
> 
> yes. Note that strsep() is the preferred API. (in fact it's 
> the only such string API that is in the kernel)

btw., for larger strings we cannot really copy into the kernel i 
suspect. We'd have to kmalloc() and that adds overhead, etc.

Nevertheless, copy_strsep_from_user() would be the symmetric API 
here.

	Ingo
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