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    Subject[tip:tracing/urgent] ftrace: Fix t_hash_start()
    Commit-ID:  d82d62444f87e5993af2fa82ed636b2206e052ea
    Gitweb: http://git.kernel.org/tip/d82d62444f87e5993af2fa82ed636b2206e052ea
    Author: Li Zefan <lizf@cn.fujitsu.com>
    AuthorDate: Wed, 24 Jun 2009 09:54:54 +0800
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Wed, 24 Jun 2009 11:02:53 +0200

    ftrace: Fix t_hash_start()

    When the output of set_ftrace_filter is larger than PAGE_SIZE,
    t_hash_start() will be called the 2nd time, and then we start
    from the head of a hlist, which is wrong and causes some entries
    to be outputed twice.

    The worse is, if the hlist is large enough, reading set_ftrace_filter
    won't stop but in a dead loop.

    Reviewed-by: Liming Wang <liming.wang@windriver.com>
    Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    LKML-Reference: <4A41876E.2060407@cn.fujitsu.com>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>


    ---
    kernel/trace/ftrace.c | 12 +++++++++++-
    1 files changed, 11 insertions(+), 1 deletions(-)

    diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
    index dc81020..71a52c1 100644
    --- a/kernel/trace/ftrace.c
    +++ b/kernel/trace/ftrace.c
    @@ -1417,10 +1417,20 @@ static void *t_hash_start(struct seq_file *m, loff_t *pos)
    {
    struct ftrace_iterator *iter = m->private;
    void *p = NULL;
    + loff_t l;
    +
    + if (!(iter->flags & FTRACE_ITER_HASH))
    + *pos = 0;

    iter->flags |= FTRACE_ITER_HASH;

    - return t_hash_next(m, p, pos);
    + iter->hidx = 0;
    + for (l = 0; l <= *pos; ) {
    + p = t_hash_next(m, p, &l);
    + if (!p)
    + break;
    + }
    + return p;
    }

    static int t_hash_show(struct seq_file *m, void *v)

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