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    Subject[PATCH] ftrace: Fix missing synchronize_rcu() removing trampoline from kallsyms
    Date
    Add synchronize_rcu() after list_del_rcu() in
    ftrace_remove_trampoline_from_kallsyms() to protect readers of
    ftrace_ops_trampoline_list (in ftrace_get_trampoline_kallsym)
    which is used when kallsyms is read.

    Fixes: fc0ea795f53c8d ("ftrace: Add symbols for ftrace trampolines")
    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    ---
    kernel/trace/ftrace.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
    index 275441254bb5..4e64367c9774 100644
    --- a/kernel/trace/ftrace.c
    +++ b/kernel/trace/ftrace.c
    @@ -2782,6 +2782,7 @@ static void ftrace_remove_trampoline_from_kallsyms(struct ftrace_ops *ops)
    {
    lockdep_assert_held(&ftrace_lock);
    list_del_rcu(&ops->list);
    + synchronize_rcu();
    }

    /*
    --
    2.17.1
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