tracing: Change event_enable/disable_read() to verify i_private != NULL
authorOleg Nesterov <oleg@redhat.com>
Fri, 26 Jul 2013 17:25:36 +0000 (19:25 +0200)
committerSteven Rostedt <rostedt@goodmis.org>
Tue, 30 Jul 2013 02:05:40 +0000 (22:05 -0400)
commitbc6f6b08dee5645770efb4b76186ded313f23752
tree4f2a94646a39b8454e21bed38f093f73c8752345
parent1a11126bcb7c93c289bf3218fa546fd3b0c0df8b
tracing: Change event_enable/disable_read() to verify i_private != NULL

tracing_open_generic_file() is racy, ftrace_event_file can be
already freed by rmdir or trace_remove_event_call().

Change event_enable_read() and event_disable_read() to read and
verify "file = i_private" under event_mutex.

This fixes nothing, but now we can change debugfs_remove("enable")
callers to nullify ->i_private and fix the the problem.

Link: http://lkml.kernel.org/r/20130726172536.GA3612@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
kernel/trace/trace_events.c