• Frederic Weisbecker's avatar
    tracing/ftrace: check if debugfs is registered before creating files · 3e1f60b8
    Frederic Weisbecker authored
    
    
    Impact: fix a crash with ftrace={nop,boot} parameter
    
    If the nop or initcall tracers are launched as boot tracers,
    they will attempt to create their option directory and files.
    But these tracers are registered very early and then assigned
    as "boot tracers" very early if asked to.
    
    Since they do this before debugfs has been registered (core initcall),
    a crash is triggered.
    
    Another early tracers could also come later. So we fix it by
    checking if debugfs is initialized before creating the root
    tracing directory.
    
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    Cc: Greg Kroah-Hartman <gregkh@suse.de>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    LKML-Reference: <1237759847-21025-3-git-send-email-fweisbec@gmail.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    3e1f60b8