[PATCH v2 17/16] xz: Remove XZ_EXTERN and extern from functions

Lasse Collin
2024-07-24T11:06:29Z

XZ_EXTERN was used to make internal functions static in the preboot code.
However, in other decompressors this hasn't been done. On x86-64, this
makes no difference to the kernel image size.

Omit XZ_EXTERN and let some of the internal functions be extern in the
preboot code. Omitting XZ_EXTERN from include/linux/xz.h fixes warnings
in "make htmldocs" and makes the intradocument links to xz_dec functions
work in Documentation/staging/xz.rst. The alternative would have been to
add "XZ_EXTERN" to c_id_attributes in Documentation/conf.py but omitting
XZ_EXTERN seemed cleaner.

Link: https://lore.kernel.org/lkml/20240723205437.3c0664b0@kaneli/
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Lasse Collin <lasse.collin@tukaani.org>
---

Notes:
This touches xz_config.h in PowerPC boot code. I haven't tested it but
zlib's functions are extern in the same context, thus this should be
a safe change on PowerPC.

This replaces the patch 8/16 ("docs: Add XZ_EXTERN to c_id_attributes"):
https://lore.kernel.org/lkml/20240721133633.47721-9-lasse.collin@tukaani.org/

Documentation/staging/xz.rst | 3 ---
arch/powerpc/boot/xz_config.h | 3 ---
include/linux/xz.h | 35 ++++++++++++-----------------------
lib/decompress_unxz.c | 1 -
lib/xz/xz_crc32.c | 4 ++--
lib/xz/xz_dec_bcj.c | 9 ++++-----
lib/xz/xz_dec_lzma2.c | 10 ++++------
lib/xz/xz_dec_stream.c | 8 ++++----
lib/xz/xz_private.h | 20 ++++++++------------
9 files changed, 34 insertions(+), 59 deletions(-)

diff --git a/Documentation/staging/xz.rst b/Documentation/staging/xz.rst
index e1054e9a8e65..6953a189e5f2 100644
--- a/Documentation/staging/xz.rst
+++ b/Documentation/staging/xz.rst
@@ -95,7 +95,4 @@ xz_dec API

This is available with ``#include <linux/xz.h>``.

-``XZ_EXTERN`` is a macro used in the preboot code. Ignore it when
-reading this documentation.
-
.. kernel-doc:: include/linux/xz.h
diff --git a/arch/powerpc/boot/xz_config.h b/arch/powerpc/boot/xz_config.h
index ebfadd39e192..9506a96ebbcc 100644
--- a/arch/powerpc/boot/xz_config.h
+++ b/arch/powerpc/boot/xz_config.h
@@ -50,11 +50,8 @@ static inline void put_unaligned_be32(u32 val, void *p)
/* prevent the inclusion of the xz-preboot MM headers */
#define DECOMPR_MM_H
#define memmove memmove
-#define XZ_EXTERN static

/* xz.h needs to be included directly since we need enum xz_mode */
#include "../../../include/linux/xz.h"

-#undef XZ_EXTERN
-
#endif
diff --git a/include/linux/xz.h b/include/linux/xz.h
index 701d62c02b9a..58ae1d746c6f 100644
--- a/include/linux/xz.h
+++ b/include/linux/xz.h
@@ -18,11 +18,6 @@
# include <stdint.h>
#endif

-/* In Linux, this is used to make extern functions static when needed. */
-#ifndef XZ_EXTERN
-# define XZ_EXTERN extern
-#endif
-
/**
* enum xz_mode - Operation mode
*
@@ -190,7 +185,7 @@ struct xz_dec;
* ready to be used with xz_dec_run(). If memory allocation fails,
* xz_dec_init() returns NULL.
*/
-XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);
+struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);

/**
* xz_dec_run() - Run the XZ decoder
@@ -210,7 +205,7 @@ XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);
* get that amount valid data from the beginning of the stream. You must use
* the multi-call decoder if you don't want to uncompress the whole stream.
*/
-XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
+enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);

/**
* xz_dec_reset() - Reset an already allocated decoder state
@@ -223,14 +218,14 @@ XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
* xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in
* multi-call mode.
*/
-XZ_EXTERN void xz_dec_reset(struct xz_dec *s);
+void xz_dec_reset(struct xz_dec *s);

/**
* xz_dec_end() - Free the memory allocated for the decoder state
* @s: Decoder state allocated using xz_dec_init(). If s is NULL,
* this function does nothing.
*/
-XZ_EXTERN void xz_dec_end(struct xz_dec *s);
+void xz_dec_end(struct xz_dec *s);

/**
* DOC: MicroLZMA decompressor
@@ -244,10 +239,6 @@ XZ_EXTERN void xz_dec_end(struct xz_dec *s);
* 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
* Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
* marker must not be used. The unused values are reserved for future use.
- *
- * These functions aren't used or available in preboot code and thus aren't
- * marked with XZ_EXTERN. This avoids warnings about static functions that
- * are never defined.
*/

/*
@@ -272,8 +263,8 @@ struct xz_dec_microlzma;
* struct xz_dec_microlzma. If memory allocation fails or
* dict_size is invalid, NULL is returned.
*/
-extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
- uint32_t dict_size);
+struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
+ uint32_t dict_size);

/**
* xz_dec_microlzma_reset() - Reset the MicroLZMA decoder state
@@ -289,9 +280,8 @@ extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
* requiring stdbool.h. This should normally be set to true.
* When this is set to false, error detection is weaker.
*/
-extern void xz_dec_microlzma_reset(struct xz_dec_microlzma *s,
- uint32_t comp_size, uint32_t uncomp_size,
- int uncomp_size_is_exact);
+void xz_dec_microlzma_reset(struct xz_dec_microlzma *s, uint32_t comp_size,
+ uint32_t uncomp_size, int uncomp_size_is_exact);

/**
* xz_dec_microlzma_run() - Run the MicroLZMA decoder
@@ -329,15 +319,14 @@ extern void xz_dec_microlzma_reset(struct xz_dec_microlzma *s,
* may be changed normally like with XZ_PREALLOC. This way input data can be
* provided from non-contiguous memory.
*/
-extern enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s,
- struct xz_buf *b);
+enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s, struct xz_buf *b);

/**
* xz_dec_microlzma_end() - Free the memory allocated for the decoder state
* @s: Decoder state allocated using xz_dec_microlzma_alloc().
* If s is NULL, this function does nothing.
*/
-extern void xz_dec_microlzma_end(struct xz_dec_microlzma *s);
+void xz_dec_microlzma_end(struct xz_dec_microlzma *s);

/*
* Standalone build (userspace build or in-kernel build for boot time use)
@@ -358,13 +347,13 @@ extern void xz_dec_microlzma_end(struct xz_dec_microlzma *s);
* This must be called before any other xz_* function to initialize
* the CRC32 lookup table.
*/
-XZ_EXTERN void xz_crc32_init(void);
+void xz_crc32_init(void);

/*
* Update CRC32 value using the polynomial from IEEE-802.3. To start a new
* calculation, the third argument must be zero. To continue the calculation,
* the previously returned value is passed as the third argument.
*/
-XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc);
+uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc);
#endif
#endif
diff --git a/lib/decompress_unxz.c b/lib/decompress_unxz.c
index cae00395d7a6..32138bb8ef77 100644
--- a/lib/decompress_unxz.c
+++ b/lib/decompress_unxz.c
@@ -107,7 +107,6 @@
#ifdef __KERNEL__
# include <linux/decompress/mm.h>
#endif
-#define XZ_EXTERN STATIC

#ifndef XZ_PREBOOT
# include <linux/slab.h>
diff --git a/lib/xz/xz_crc32.c b/lib/xz/xz_crc32.c
index effdf34ec48d..6a7906a328ba 100644
--- a/lib/xz/xz_crc32.c
+++ b/lib/xz/xz_crc32.c
@@ -26,7 +26,7 @@

STATIC_RW_DATA uint32_t xz_crc32_table[256];

-XZ_EXTERN void xz_crc32_init(void)
+void xz_crc32_init(void)
{
const uint32_t poly = 0xEDB88320;

@@ -45,7 +45,7 @@ XZ_EXTERN void xz_crc32_init(void)
return;
}

-XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
+uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
{
crc = ~crc;

diff --git a/lib/xz/xz_dec_bcj.c b/lib/xz/xz_dec_bcj.c
index 42d7f268726f..8237db17eee3 100644
--- a/lib/xz/xz_dec_bcj.c
+++ b/lib/xz/xz_dec_bcj.c
@@ -572,9 +572,8 @@ static void bcj_flush(struct xz_dec_bcj *s, struct xz_buf *b)
* data in chunks of 1-16 bytes. To hide this issue, this function does
* some buffering.
*/
-XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
- struct xz_dec_lzma2 *lzma2,
- struct xz_buf *b)
+enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s, struct xz_dec_lzma2 *lzma2,
+ struct xz_buf *b)
{
size_t out_start;

@@ -682,7 +681,7 @@ XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
return s->ret;
}

-XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call)
+struct xz_dec_bcj *xz_dec_bcj_create(bool single_call)
{
struct xz_dec_bcj *s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s != NULL)
@@ -691,7 +690,7 @@ XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call)
return s;
}

-XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
+enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
{
switch (id) {
#ifdef XZ_DEC_X86
diff --git a/lib/xz/xz_dec_lzma2.c b/lib/xz/xz_dec_lzma2.c
index 613939f5dd6c..83bb66b6016d 100644
--- a/lib/xz/xz_dec_lzma2.c
+++ b/lib/xz/xz_dec_lzma2.c
@@ -960,8 +960,7 @@ static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b)
* Take care of the LZMA2 control layer, and forward the job of actual LZMA
* decoding or copying of uncompressed chunks to other functions.
*/
-XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
- struct xz_buf *b)
+enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, struct xz_buf *b)
{
uint32_t tmp;

@@ -1137,8 +1136,7 @@ XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
return XZ_OK;
}

-XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
- uint32_t dict_max)
+struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode, uint32_t dict_max)
{
struct xz_dec_lzma2 *s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
@@ -1161,7 +1159,7 @@ XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
return s;
}

-XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props)
+enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props)
{
/* This limits dictionary size to 3 GiB to keep parsing simpler. */
if (props > 39)
@@ -1197,7 +1195,7 @@ XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props)
return XZ_OK;
}

-XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s)
+void xz_dec_lzma2_end(struct xz_dec_lzma2 *s)
{
if (DEC_IS_MULTI(s->dict.mode))
vfree(s->dict.buf);
diff --git a/lib/xz/xz_dec_stream.c b/lib/xz/xz_dec_stream.c
index 0058406ccd17..f9d003684d56 100644
--- a/lib/xz/xz_dec_stream.c
+++ b/lib/xz/xz_dec_stream.c
@@ -746,7 +746,7 @@ static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)
* actually succeeds (that's the price to pay of using the output buffer as
* the workspace).
*/
-XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
+enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
{
size_t in_start;
size_t out_start;
@@ -782,7 +782,7 @@ XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b)
return ret;
}

-XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
+struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
{
struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
@@ -812,7 +812,7 @@ XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
return NULL;
}

-XZ_EXTERN void xz_dec_reset(struct xz_dec *s)
+void xz_dec_reset(struct xz_dec *s)
{
s->sequence = SEQ_STREAM_HEADER;
s->allow_buf_error = false;
@@ -824,7 +824,7 @@ XZ_EXTERN void xz_dec_reset(struct xz_dec *s)
s->temp.size = STREAM_HEADER_SIZE;
}

-XZ_EXTERN void xz_dec_end(struct xz_dec *s)
+void xz_dec_end(struct xz_dec *s)
{
if (s != NULL) {
xz_dec_lzma2_end(s->lzma2);
diff --git a/lib/xz/xz_private.h b/lib/xz/xz_private.h
index a8b1cbe8d21d..5f1294a1408c 100644
--- a/lib/xz/xz_private.h
+++ b/lib/xz/xz_private.h
@@ -115,8 +115,7 @@
* Allocate memory for LZMA2 decoder. xz_dec_lzma2_reset() must be used
* before calling xz_dec_lzma2_run().
*/
-XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
- uint32_t dict_max);
+struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode, uint32_t dict_max);

/*
* Decode the LZMA2 properties (one byte) and reset the decoder. Return
@@ -124,22 +123,20 @@ XZ_EXTERN struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode,
* big enough, and XZ_OPTIONS_ERROR if props indicates something that this
* decoder doesn't support.
*/
-XZ_EXTERN enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s,
- uint8_t props);
+enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props);

/* Decode raw LZMA2 stream from b->in to b->out. */
-XZ_EXTERN enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
- struct xz_buf *b);
+enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, struct xz_buf *b);

/* Free the memory allocated for the LZMA2 decoder. */
-XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s);
+void xz_dec_lzma2_end(struct xz_dec_lzma2 *s);

#ifdef XZ_DEC_BCJ
/*
* Allocate memory for BCJ decoders. xz_dec_bcj_reset() must be used before
* calling xz_dec_bcj_run().
*/
-XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call);
+struct xz_dec_bcj *xz_dec_bcj_create(bool single_call);

/*
* Decode the Filter ID of a BCJ filter. This implementation doesn't
@@ -147,16 +144,15 @@ XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call);
* is needed. Returns XZ_OK if the given Filter ID is supported.
* Otherwise XZ_OPTIONS_ERROR is returned.
*/
-XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id);
+enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id);

/*
* Decode raw BCJ + LZMA2 stream. This must be used only if there actually is
* a BCJ filter in the chain. If the chain has only LZMA2, xz_dec_lzma2_run()
* must be called directly.
*/
-XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
- struct xz_dec_lzma2 *lzma2,
- struct xz_buf *b);
+enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s, struct xz_dec_lzma2 *lzma2,
+ struct xz_buf *b);

/* Free the memory allocated for the BCJ filters. */
#define xz_dec_bcj_end(s) kfree(s)
--
2.45.2