Revision 4a23717a236b2ab31efb1651f586126789fc997f authored by Davidlohr Bueso on 13 December 2014, 00:54:30 UTC, committed by Linus Torvalds on 13 December 2014, 20:42:45 UTC
Both register and unregister call build_map_info() in order to create the list of mappings before installing or removing breakpoints for every mm which maps file backed memory. As such, there is no reason to hold the i_mmap_rwsem exclusively, so share it and allow concurrent readers to build the mapping data. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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decompress.c
/*
* decompress.c
*
* Detect the decompression method based on magic number
*/
#include <linux/decompress/generic.h>
#include <linux/decompress/bunzip2.h>
#include <linux/decompress/unlzma.h>
#include <linux/decompress/unxz.h>
#include <linux/decompress/inflate.h>
#include <linux/decompress/unlzo.h>
#include <linux/decompress/unlz4.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/printk.h>
#ifndef CONFIG_DECOMPRESS_GZIP
# define gunzip NULL
#endif
#ifndef CONFIG_DECOMPRESS_BZIP2
# define bunzip2 NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZMA
# define unlzma NULL
#endif
#ifndef CONFIG_DECOMPRESS_XZ
# define unxz NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZO
# define unlzo NULL
#endif
#ifndef CONFIG_DECOMPRESS_LZ4
# define unlz4 NULL
#endif
struct compress_format {
unsigned char magic[2];
const char *name;
decompress_fn decompressor;
};
static const struct compress_format compressed_formats[] __initconst = {
{ {037, 0213}, "gzip", gunzip },
{ {037, 0236}, "gzip", gunzip },
{ {0x42, 0x5a}, "bzip2", bunzip2 },
{ {0x5d, 0x00}, "lzma", unlzma },
{ {0xfd, 0x37}, "xz", unxz },
{ {0x89, 0x4c}, "lzo", unlzo },
{ {0x02, 0x21}, "lz4", unlz4 },
{ {0, 0}, NULL, NULL }
};
decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
const char **name)
{
const struct compress_format *cf;
if (len < 2)
return NULL; /* Need at least this much... */
pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
for (cf = compressed_formats; cf->name; cf++) {
if (!memcmp(inbuf, cf->magic, 2))
break;
}
if (name)
*name = cf->name;
return cf->decompressor;
}
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