From: Frederic Weisbecker Date: Sun, 22 Mar 2009 22:10:45 +0000 (+0100) Subject: tracing/ftrace: check if debugfs is registered before creating files X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=3e1f60b80cafcb5d7e8d3665b35962fbb8fb9efa;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git tracing/ftrace: check if debugfs is registered before creating files 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: Frederic Weisbecker Cc: Greg Kroah-Hartman Cc: Steven Rostedt LKML-Reference: <1237759847-21025-3-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ace685c70186..f0e1337b1ebd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3513,6 +3513,9 @@ struct dentry *tracing_init_dentry(void) if (d_tracer) return d_tracer; + if (!debugfs_initialized()) + return NULL; + d_tracer = debugfs_create_dir("tracing", NULL); if (!d_tracer && !once) {