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tracing: Kill trace_create_file_ops() and friends

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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 <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Oleg Nesterov 2013-07-31 19:31:32 +02:00 committed by Steven Rostedt
parent 3ddc77f6f4
commit 779c5e3791
1 changed files with 9 additions and 144 deletions
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153
kernel/trace/trace_events.c
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@ -1683,8 +1683,7 @@ __trace_early_add_new_event(struct ftrace_event_call *call,
}
struct ftrace_module_file_ops;
static void __add_event_to_tracers(struct ftrace_event_call *call,
struct ftrace_module_file_ops *file_ops);
static void __add_event_to_tracers(struct ftrace_event_call *call);
/* Add an additional event_call dynamically */
int trace_add_event_call(struct ftrace_event_call *call)
@ -1695,7 +1694,7 @@ int trace_add_event_call(struct ftrace_event_call *call)
ret = __register_event(call, NULL);
if (ret >= 0)
__add_event_to_tracers(call, NULL);
__add_event_to_tracers(call);
mutex_unlock(&event_mutex);
mutex_unlock(&trace_types_lock);
@ -1769,100 +1768,21 @@ int trace_remove_event_call(struct ftrace_event_call *call)
#ifdef CONFIG_MODULES
static LIST_HEAD(ftrace_module_file_list);
/*
* Modules must own their file_operations to keep up with
* reference counting.
*/
struct ftrace_module_file_ops {
struct list_head list;
struct module *mod;
struct file_operations id;
struct file_operations enable;
struct file_operations format;
struct file_operations filter;
};
static struct ftrace_module_file_ops *
find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
{
/*
* As event_calls are added in groups by module,
* when we find one file_ops, we don't need to search for
* each call in that module, as the rest should be the
* same. Only search for a new one if the last one did
* not match.
*/
if (file_ops && mod == file_ops->mod)
return file_ops;
list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
if (file_ops->mod == mod)
return file_ops;
}
return NULL;
}
static struct ftrace_module_file_ops *
trace_create_file_ops(struct module *mod)
{
struct ftrace_module_file_ops *file_ops;
/*
* This is a bit of a PITA. To allow for correct reference
* counting, modules must "own" their file_operations.
* To do this, we allocate the file operations that will be
* used in the event directory.
*/
file_ops = kmalloc(sizeof(*file_ops), GFP_KERNEL);
if (!file_ops)
return NULL;
file_ops->mod = mod;
file_ops->id = ftrace_event_id_fops;
file_ops->id.owner = mod;
file_ops->enable = ftrace_enable_fops;
file_ops->enable.owner = mod;
file_ops->filter = ftrace_event_filter_fops;
file_ops->filter.owner = mod;
file_ops->format = ftrace_event_format_fops;
file_ops->format.owner = mod;
list_add(&file_ops->list, &ftrace_module_file_list);
return file_ops;
}
static void trace_module_add_events(struct module *mod)
{
struct ftrace_module_file_ops *file_ops = NULL;
struct ftrace_event_call **call, **start, **end;
start = mod->trace_events;
end = mod->trace_events + mod->num_trace_events;
if (start == end)
return;
file_ops = trace_create_file_ops(mod);
if (!file_ops)
return;
for_each_event(call, start, end) {
__register_event(*call, mod);
__add_event_to_tracers(*call, file_ops);
__add_event_to_tracers(*call);
}
}
static void trace_module_remove_events(struct module *mod)
{
struct ftrace_module_file_ops *file_ops;
struct ftrace_event_call *call, *p;
bool clear_trace = false;
@ -1874,16 +1794,6 @@ static void trace_module_remove_events(struct module *mod)
__trace_remove_event_call(call);
}
}
/* Now free the file_operations */
list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
if (file_ops->mod == mod)
break;
}
if (&file_ops->list != &ftrace_module_file_list) {
list_del(&file_ops->list);
kfree(file_ops);
}
up_write(&trace_event_sem);
/*
@ -1919,62 +1829,22 @@ static int trace_module_notify(struct notifier_block *self,
return 0;
}
static int
__trace_add_new_mod_event(struct ftrace_event_call *call,
struct trace_array *tr,
struct ftrace_module_file_ops *file_ops)
{
return __trace_add_new_event(call, tr,
&file_ops->id, &file_ops->enable,
&file_ops->filter, &file_ops->format);
}
#else
static inline struct ftrace_module_file_ops *
find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
{
return NULL;
}
static inline int trace_module_notify(struct notifier_block *self,
unsigned long val, void *data)
{
return 0;
}
static inline int
__trace_add_new_mod_event(struct ftrace_event_call *call,
struct trace_array *tr,
struct ftrace_module_file_ops *file_ops)
{
return -ENODEV;
}
#endif /* CONFIG_MODULES */
/* Create a new event directory structure for a trace directory. */
static void
__trace_add_event_dirs(struct trace_array *tr)
{
struct ftrace_module_file_ops *file_ops = NULL;
struct ftrace_event_call *call;
int ret;
list_for_each_entry(call, &ftrace_events, list) {
if (call->mod) {
/*
* Directories for events by modules need to
* keep module ref counts when opened (as we don't
* want the module to disappear when reading one
* of these files). The file_ops keep account of
* the module ref count.
*/
file_ops = find_ftrace_file_ops(file_ops, call->mod);
if (!file_ops)
continue; /* Warn? */
ret = __trace_add_new_mod_event(call, tr, file_ops);
if (ret < 0)
pr_warning("Could not create directory for event %s\n",
call->name);
continue;
}
ret = __trace_add_new_event(call, tr,
&ftrace_event_id_fops,
&ftrace_enable_fops,
@ -2332,21 +2202,16 @@ __trace_remove_event_dirs(struct trace_array *tr)
remove_event_file_dir(file);
}
static void
__add_event_to_tracers(struct ftrace_event_call *call,
struct ftrace_module_file_ops *file_ops)
static void __add_event_to_tracers(struct ftrace_event_call *call)
{
struct trace_array *tr;
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
if (file_ops)
__trace_add_new_mod_event(call, tr, file_ops);
else
__trace_add_new_event(call, tr,
&ftrace_event_id_fops,
&ftrace_enable_fops,
&ftrace_event_filter_fops,
&ftrace_event_format_fops);
__trace_add_new_event(call, tr,
&ftrace_event_id_fops,
&ftrace_enable_fops,
&ftrace_event_filter_fops,
&ftrace_event_format_fops);
}
}