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    SubjectRe: [PATCH] dma_declare_coherent_memory wrong allocation
    On Sun, 22 Apr 2007, James Bottomley wrote:

    > On Fri, 2007-04-13 at 20:08 +0200, Guennadi Liakhovetski wrote:
    > > - int bitmap_size = (pages + 31)/32;
    > > + int bitmap_size = DIV_ROUND_UP(pages, 8);
    >
    > This isn't quite right. Bitmaps are arrays of longs, not arrays of
    > bytes. The bug is forgetting that kmalloc() takes bytes ...
    >
    > How about
    >
    > int bitmap_size = DIV_ROUNDUP(pages, 32) * 4;

    Right, thinko. How about using his:

    + int pages = DIV_ROUND_UP(size, PAGE_SIZE);
    + int bitmap_size = BITS_TO_LONGS(pages) * BYTES_PER_LONG;

    to also allow for size not an integer number of pages as Andrew noticed?
    This could be done in 2 patches:

    ---
    Introduce BYTES_PER_LONG and remove local definitions. fbsys
    compile-tested, amifb untested (framebuffer maintainer cc'ed)...

    Signed-off-by: G. Liakhovetski <g.liakhovetski@gmx.de>

    --- a/include/linux/types.h 2007-04-15 22:07:52.000000000 +0200
    +++ b/include/linux/types.h 2007-04-22 22:51:17.000000000 +0200
    @@ -9,6 +9,7 @@
    unsigned long name[BITS_TO_LONGS(bits)]

    #define BITS_PER_BYTE 8
    +#define BYTES_PER_LONG (BITS_PER_LONG / BITS_PER_BYTE)
    #endif

    #include <linux/posix_types.h>
    diff --git a/drivers/video/fbsysfs.c b/drivers/video/fbsysfs.c
    index 40c80c8..6bb68b8 100644
    --- a/drivers/video/fbsysfs.c
    +++ b/drivers/video/fbsysfs.c
    @@ -19,6 +19,7 @@
    #include <linux/fb.h>
    #include <linux/console.h>
    #include <linux/module.h>
    +#include <linux/types.h>

    #define FB_SYSFS_FLAG_ATTR 1

    @@ -37,7 +38,6 @@
    */
    struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
    {
    -#define BYTES_PER_LONG (BITS_PER_LONG/8)
    #define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
    int fb_info_size = sizeof(struct fb_info);
    struct fb_info *info;
    diff --git a/drivers/video/amifb.c b/drivers/video/amifb.c
    index 1a849b8..a53d5a2 100644
    --- a/drivers/video/amifb.c
    +++ b/drivers/video/amifb.c
    @@ -51,6 +51,8 @@
    #include <linux/fb.h>
    #include <linux/init.h>
    #include <linux/ioport.h>
    +#include <linux/types.h>
    +#include <linux/log2.h>

    #include <asm/uaccess.h>
    #include <asm/system.h>
    @@ -1350,15 +1352,7 @@ static int amifb_pan_display(struct fb_var_screeninfo *var,
    }


    -#if BITS_PER_LONG == 32
    -#define BYTES_PER_LONG 4
    -#define SHIFT_PER_LONG 5
    -#elif BITS_PER_LONG == 64
    -#define BYTES_PER_LONG 8
    -#define SHIFT_PER_LONG 6
    -#else
    -#define Please update me
    -#endif
    +#define SHIFT_PER_LONG ilog2(BITS_PER_LONG)


    /*
    -
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