[lkml]   [2007]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: sys_write() racy for multi-threaded append?
    Michael K. Edwards <> wrote:

    > On 3/8/07, Eric Dumazet <> wrote:
    >> Absolutely not. We dont want to slow down kernel 'just in case a fool might
    >> want to do crazy things'
    > Actually, I think it would make the kernel (negligibly) faster to bump
    > f_pos before the vfs_write() call.

    This is a security risk.

    other process:

    Thread 1:
    write(fd, large)

    Thread 2:
    fseek(fd, -n, relative)
    read(fd, buf)

    BTW: The best thing you can do to a program where two threads race for
    writing one fd is to let it crash and burn in the most spectacular way
    allowed without affecting the rest of the system, unless it happens to
    be a pipe and the number of bytes written is less than PIPE_MAX.
    The secret of the universe is #@*%! NO CARRIER

    Friß, Spammer:
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-03-12 08:57    [W:0.020 / U:14.076 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site