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    SubjectRe: [PATCH 4/4] tracing: fix splice return too large
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    On Wed, 2009-04-08 at 11:55 +0200, Ingo Molnar wrote:
    > * Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
    >
    > > Ingo Molnar wrote:
    > > > * Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
    > > >
    > > >> - for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
    > > >> + if (*ppos & (PAGE_SIZE - 1)) {
    > > >> + WARN_ONCE(1, "Ftrace: previous read must page-align\n");

    Small English grammar nit,

    "Ftrace: previous read must be page-aligned"

    > > >> + return -EINVAL;
    > > >> + }
    > > >> +
    > > >> + if (len & (PAGE_SIZE - 1)) {
    > > >> + WARN_ONCE(1, "Ftrace: splice_read should page-align\n");

    "Ftrace: splice_read should be page-aligned"

    > > >> + if (len < PAGE_SIZE)
    > > >> + return -EINVAL;
    > > >> + len &= PAGE_MASK;
    > > >> + }
    > > >
    > > > Hm, the fix looks good, but is it a good idea to allow the
    > > > triggering of this message from user-space?
    > > >
    > >
    > > But it is only triggered once.
    > >
    > > If user get content from trace_pipe_raw with non-page-align, the
    > > content is garbage. It's wasting, the kernel disallows it. This
    > > message tell user why he read failed.
    > >
    > > These 4 patches make trace_pipe_raw more robustious and consistent
    > > (read by read(2) and splice). I focus on handling raw ftrace data
    > > in userspace, these raw ftrace data should be trustiness.
    >
    > Ok, agreed.
    >
    > i've applied these four fixes from you to tip:tracing/splice,
    > thanks. Steve: i think they are tracing/urgent material - do you
    > agree?

    Agreed. With my comments above:

    Acked-by: Steven Rostedt <rostedt@goodmis.org>

    -- Steve




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