linux/kernel/trace/trace_events.c, branch v3.12

tracing: Kill the !CONFIG_MODULES code in trace_events.c

2013-08-22T03:28:03Z

Move trace_module_nb under CONFIG_MODULES and kill the dummy trace_module_notify(). Imho it doesn't make sense to define "struct notifier_block" and its .notifier_call just to avoid "ifdef" in event_trace_init(), and all other !CONFIG_MODULES code has already gone away. Link: http://lkml.kernel.org/r/20130731173137.GA31043@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Don't pass file_operations array to event_create_dir()

2013-08-22T03:25:06Z

Now that event_create_dir() and __trace_add_new_event() always use the same file_operations we can kill these arguments and simplify the code. Link: http://lkml.kernel.org/r/20130731173135.GA31040@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Kill trace_create_file_ops() and friends

2013-08-22T02:31:23Z

trace_create_file_ops() allocates the copy of id/filter/format/enable file_operations to set "f_op->owner = mod" for fops_get(). However after the recent changes there is no reason to prevent rmmod even if one of these files is opened. A file operation can do nothing but fail after remove_event_file_dir() clears ->i_private for every file removed by trace_module_remove_events(). Kill "struct ftrace_module_file_ops" and fix the compilation errors. Link: http://lkml.kernel.org/r/20130731173132.GA31033@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Add comment to describe special break case in probe_remove_event_call()

2013-07-31T17:16:22Z

The "break" used in the do_for_each_event_file() is used as an optimization as the loop is really a double loop. The loop searches all event files for each trace_array. There's only one matching event file per trace_array and after we find the event file for the trace_array, the break is used to jump to the next trace_array and start the search there. As this is not a standard way of using "break" in C code, it requires a comment right before the break to let people know what is going on. Signed-off-by: Steven Rostedt

tracing: trace_remove_event_call() should fail if call/file is in use

2013-07-31T17:12:48Z

Change trace_remove_event_call(call) to return the error if this call is active. This is what the callers assume but can't verify outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c need the additional changes, unregister_trace_probe() should abort if trace_remove_event_call() fails. The caller is going to free this call/file so we must ensure that nobody can use them after trace_remove_event_call() succeeds. debugfs should be fine after the previous changes and event_remove() does TRACE_REG_UNREGISTER, but still there are 2 reasons why we need the additional checks: - There could be a perf_event(s) attached to this tp_event, so the patch checks ->perf_refcount. - TRACE_REG_UNREGISTER can be suppressed by FTRACE_EVENT_FL_SOFT_MODE, so we simply check FTRACE_EVENT_FL_ENABLED protected by event_mutex. Link: http://lkml.kernel.org/r/20130729175033.GB26284@redhat.com Reviewed-by: Masami Hiramatsu Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private

2013-07-30T02:57:11Z

Change remove_event_file_dir() to clear ->i_private for every file we are going to remove. We need to check file->dir != NULL because event_create_dir() can fail. debugfs_remove_recursive(NULL) is fine but the patch moves it under the same check anyway for readability. spin_lock(d_lock) and "d_inode != NULL" check are not needed afaics, but I do not understand this code enough. tracing_open_generic_file() and tracing_release_generic_file() can go away, ftrace_enable_fops and ftrace_event_filter_fops() use tracing_open_generic() but only to check tracing_disabled. This fixes all races with event_remove() or instance_delete(). f_op->read/write/whatever can never use the freed file/call, all event/* files were changed to check and use ->i_private under event_mutex. Note: this doesn't not fix other problems, event_remove() can destroy the active ftrace_event_call, we need more changes but those changes are completely orthogonal. Link: http://lkml.kernel.org/r/20130728183527.GB16723@redhat.com Reviewed-by: Masami Hiramatsu Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Introduce remove_event_file_dir()

2013-07-30T02:57:10Z

Preparation for the next patch. Extract the common code from remove_event_from_tracers() and __trace_remove_event_dirs() into the new helper, remove_event_file_dir(). The patch looks more complicated than it actually is, it also moves remove_subsystem() up to avoid the forward declaration. Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com Reviewed-by: Masami Hiramatsu Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Change f_start() to take event_mutex and verify i_private != NULL

2013-07-30T02:57:10Z

trace_format_open() and trace_format_seq_ops are racy, nothing protects ftrace_event_call from trace_remove_event_call(). Change f_start() to take event_mutex and verify i_private != NULL, change f_stop() to drop this lock. This fixes nothing, but now we can change debugfs_remove("format") callers to nullify ->i_private and fix the the problem. Note: the usage of event_mutex is sub-optimal but simple, we can change this later. Link: http://lkml.kernel.org/r/20130726172543.GA3622@redhat.com Reviewed-by: Masami Hiramatsu Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Change event_filter_read/write to verify i_private != NULL

2013-07-30T02:56:59Z

event_filter_read/write() are racy, ftrace_event_call can be already freed by trace_remove_event_call() callers. 1. Shift mutex_lock(event_mutex) from print/apply_event_filter to the callers. 2. Change the callers, event_filter_read() and event_filter_write() to read i_private under this mutex and abort if it is NULL. This fixes nothing, but now we can change debugfs_remove("filter") callers to nullify ->i_private and fix the the problem. Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com Reviewed-by: Masami Hiramatsu Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt

tracing: Change event_enable/disable_read() to verify i_private != NULL

2013-07-30T02:05:40Z

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 Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt