[PATCH] zlib_inflate: Upgrade library code to a recent version

Upgrade the zlib_inflate implementation in the kernel from a patched
version 1.1.3/4 to a patched 1.2.3.

The code in the kernel is about seven years old and I noticed that the
external zlib library's inflate performance was significantly faster (~50%)
than the code in the kernel on ARM (and faster again on x86_32).

For comparison the newer deflate code is 20% slower on ARM and 50% slower
on x86_32 but gives an approx 1% compression ratio improvement.  I don't
consider this to be an improvement for kernel use so have no plans to
change the zlib_deflate code.

Various changes have been made to the zlib code in the kernel, the most
significant being the extra functions/flush option used by ppp_deflate.
This update reimplements the features PPP needs to ensure it continues to
work.

This code has been tested on ARM under both JFFS2 (with zlib compression
enabled) and ppp_deflate and on x86_32.  JFFS2 sees an approx.  10% real
world file read speed improvement.

This patch also removes ZLIB_VERSION as it no longer has a correct value.
We don't need version checks anyway as the kernel's module handling will
take care of that for us.  This removal is also more in keeping with the
zlib author's wishes (http://www.zlib.net/zlib_faq.html#faq24) and I've
added something to the zlib.h header to note its a modified version.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 23 deletions

diff --git a/lib/zlib_deflate/deflate.c b/lib/zlib_deflate/deflate.c
index 1653dd9bb01a..c3e4a2baf835 100644
--- a/lib/zlib_deflate/deflate.c
+++ b/lib/zlib_deflate/deflate.c
@@ -164,34 +164,17 @@ static const config configuration_table[10] = {
     memset((char *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
 
 /* ========================================================================= */
-int zlib_deflateInit_(
-        z_streamp strm,
-        int level,
-        const char *version,
-        int stream_size
-)
-{
-    return zlib_deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS,
-                              DEF_MEM_LEVEL,
-                              Z_DEFAULT_STRATEGY, version, stream_size);
-    /* To do: ignore strm->next_in if we use it as window */
-}
-
-/* ========================================================================= */
-int zlib_deflateInit2_(
+int zlib_deflateInit2(
         z_streamp strm,
         int  level,
         int  method,
         int  windowBits,
         int  memLevel,
-        int  strategy,
-        const char *version,
-        int stream_size
+        int  strategy
 )
 {
     deflate_state *s;
     int noheader = 0;
-    static char* my_version = ZLIB_VERSION;
     deflate_workspace *mem;
 
     ush *overlay;
@@ -199,10 +182,6 @@ int zlib_deflateInit2_(
      * output size for (length,distance) codes is <= 24 bits.
      */
 
-    if (version == NULL || version[0] != my_version[0] ||
-        stream_size != sizeof(z_stream)) {
-        return Z_VERSION_ERROR;
-    }
     if (strm == NULL) return Z_STREAM_ERROR;
 
     strm->msg = NULL;