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    Subject[tip:perf/probes] tracing/kprobes: Fix trace_probe registration order
    Commit-ID:  2d5e067edc4635ff7515bfa9ab3edb38bc344cab
    Gitweb: http://git.kernel.org/tip/2d5e067edc4635ff7515bfa9ab3edb38bc344cab
    Author: Masami Hiramatsu <mhiramat@redhat.com>
    AuthorDate: Mon, 14 Sep 2009 16:48:56 -0400
    Committer: Frederic Weisbecker <fweisbec@gmail.com>
    CommitDate: Thu, 17 Sep 2009 04:03:40 +0200

    tracing/kprobes: Fix trace_probe registration order

    Fix trace_probe registration order. ftrace_event_call and ftrace_event
    must be registered before kprobe/kretprobe, because tracing/profiling
    handlers dereference the event-id.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Acked-by: Steven Rostedt <rostedt@goodmis.org>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Frank Ch. Eigler <fche@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Jason Baron <jbaron@redhat.com>
    Cc: K.Prasad <prasad@linux.vnet.ibm.com>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    Cc: Li Zefan <lizf@cn.fujitsu.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Cc: Tom Zanussi <tzanussi@gmail.com>
    LKML-Reference: <20090914204856.18779.52961.stgit@dhcp-100-2-132.bos.redhat.com>
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    ---
    kernel/trace/trace_kprobe.c | 42 +++++++++++++++++++-----------------------
    1 files changed, 19 insertions(+), 23 deletions(-)

    diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
    index cbc0870..ea0db8e 100644
    --- a/kernel/trace/trace_kprobe.c
    +++ b/kernel/trace/trace_kprobe.c
    @@ -347,20 +347,15 @@ static struct trace_probe *find_probe_event(const char *event)
    return NULL;
    }

    -static void __unregister_trace_probe(struct trace_probe *tp)
    +/* Unregister a trace_probe and probe_event: call with locking probe_lock */
    +static void unregister_trace_probe(struct trace_probe *tp)
    {
    if (probe_is_return(tp))
    unregister_kretprobe(&tp->rp);
    else
    unregister_kprobe(&tp->rp.kp);
    -}
    -
    -/* Unregister a trace_probe and probe_event: call with locking probe_lock */
    -static void unregister_trace_probe(struct trace_probe *tp)
    -{
    - unregister_probe_event(tp);
    - __unregister_trace_probe(tp);
    list_del(&tp->list);
    + unregister_probe_event(tp);
    }

    /* Register a trace_probe and probe_event */
    @@ -371,6 +366,19 @@ static int register_trace_probe(struct trace_probe *tp)

    mutex_lock(&probe_lock);

    + /* register as an event */
    + old_tp = find_probe_event(tp->call.name);
    + if (old_tp) {
    + /* delete old event */
    + unregister_trace_probe(old_tp);
    + free_trace_probe(old_tp);
    + }
    + ret = register_probe_event(tp);
    + if (ret) {
    + pr_warning("Faild to register probe event(%d)\n", ret);
    + goto end;
    + }
    +
    if (probe_is_return(tp))
    ret = register_kretprobe(&tp->rp);
    else
    @@ -384,21 +392,9 @@ static int register_trace_probe(struct trace_probe *tp)
    tp->rp.kp.addr);
    ret = -EINVAL;
    }
    - goto end;
    - }
    - /* register as an event */
    - old_tp = find_probe_event(tp->call.name);
    - if (old_tp) {
    - /* delete old event */
    - unregister_trace_probe(old_tp);
    - free_trace_probe(old_tp);
    - }
    - ret = register_probe_event(tp);
    - if (ret) {
    - pr_warning("Faild to register probe event(%d)\n", ret);
    - __unregister_trace_probe(tp);
    - }
    - list_add_tail(&tp->list, &probe_list);
    + unregister_probe_event(tp);
    + } else
    + list_add_tail(&tp->list, &probe_list);
    end:
    mutex_unlock(&probe_lock);
    return ret;

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