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SubjectRe: [RFC] [-mm] Remove 'unsafe' LZO decompressor
On Thu, 24 May 2007 18:15:17 +0100
Michael-Luke Jones <mlj28@cam.ac.uk> wrote:

> Attached is a patch which may be desirable for -mm. It applies
> directly to 2.6.22-rc2-mm1.
>
> The patch removes the 'unsafe' LZO decompression function, lowering
> the size of the minilzo.c file by nearly 500 out of an original 1727
> lines. It also removes references to the 'unsafe' decompression
> function in the public LZO header and the EXPORT_SYMBOL_GPL declaration.
>
> This is intended to provoke some discussion over whether a
> decompression function able to scribble on arbitrary memory is
> desirable in the mainline kernel, whatever the performance increases.
>
> Over and above the security/stability implications of using this
> code, it can also be argued to represent an unnecessary duplication
> of the vast majority of LZO decompression code. This is due to the
> lack of likely in-kernel uses of the 'unsafe' function.
>
> Only a single user for this 'unsafe' code has been suggested, the
> 'Compressed Caching' project. This code is highly unlikely to move
> into mainline in the same timeframe as the LZO code. All of the other
> suggested uses require decompression of untrusted data, such that the
> 'safe' function should be used.
>
> Comments / disagreement all welcome :)

This is obviously a highly desirable thing to do for a number of reasons.
But have we quantified the performance difference?
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