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    Subject[PATCH] /dev/mem: Allow rewinding
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    Le lundi 05 avril 2010 à 23:04 +0200, Eric Dumazet a écrit :
    > Andrew, commit dcefafb6ac90ece8d68a6c203105f3d313e52da4 seems to be the
    > problem.
    >
    > It breaks rewinds (negative offsets to lseek (... SEEK_CUR))
    >

    Here is a patch to make rewind working again on /dev/mem

    [PATCH] /dev/mem: Allow rewinding

    commit dcefafb6 (/dev/mem: dont allow seek to last page)
    inadvertently disabled rewinding on /dev/mem.

    This broke x86info for example.

    Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
    ---
    diff --git a/drivers/char/mem.c b/drivers/char/mem.c
    index 1f3215a..3973a1d 100644
    --- a/drivers/char/mem.c
    +++ b/drivers/char/mem.c
    @@ -710,11 +710,6 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
    switch (orig) {
    case SEEK_CUR:
    offset += file->f_pos;
    - if ((unsigned long long)offset <
    - (unsigned long long)file->f_pos) {
    - ret = -EOVERFLOW;
    - break;
    - }
    case SEEK_SET:
    /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
    if ((unsigned long long)offset >= ~0xFFFULL) {

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