Commit 3e1f60b8 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar

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: 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>
parent c0f92ba9
......@@ -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) {
......
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