[Patch v2 4/4] tracing: make tracing_init_dentry() returns an integer instead of a d_entry pointer

From: Wei Yang
Date: Sat Jul 11 2020 - 21:12:31 EST

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Current tracing_init_dentry() return a d_entry pointer, while is not
necessary. This function returns NULL on success or error on failure,
which means there is no valid d_entry pointer return.

Let's return 0 on success and negative value for error.

Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 36 ++++++++++++++--------------
kernel/trace/trace.h | 2 +-
kernel/trace/trace_dynevent.c | 8 +++----
kernel/trace/trace_events_synth.c | 9 +++----
kernel/trace/trace_functions_graph.c | 8 +++----
kernel/trace/trace_hwlat.c | 8 +++----
kernel/trace/trace_kprobe.c | 10 ++++----
kernel/trace/trace_printk.c | 8 +++----
kernel/trace/trace_stack.c | 12 +++++-----
kernel/trace/trace_stat.c | 8 +++----
kernel/trace/trace_uprobe.c | 9 ++++---
11 files changed, 57 insertions(+), 61 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 547e1e01902a..41c3d75c34cc 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8933,23 +8933,23 @@ static struct vfsmount *trace_automount(struct dentry *mntpt, void *ingore)
* directory. It is called via fs_initcall() by any of the boot up code
* and expects to return the dentry of the top level tracing directory.
*/
-struct dentry *tracing_init_dentry(void)
+int tracing_init_dentry(void)
{
struct trace_array *tr = &global_trace;

if (security_locked_down(LOCKDOWN_TRACEFS)) {
pr_warn("Tracing disabled due to lockdown\n");
- return ERR_PTR(-EPERM);
+ return -EPERM;
}

/* The top level trace array uses NULL as parent */
if (tr->dir)
- return NULL;
+ return 0;

if (WARN_ON(!tracefs_initialized()) ||
(IS_ENABLED(CONFIG_DEBUG_FS) &&
WARN_ON(!debugfs_initialized())))
- return ERR_PTR(-ENODEV);
+ return -ENODEV;

/*
* As there may still be users that expect the tracing
@@ -8960,7 +8960,7 @@ struct dentry *tracing_init_dentry(void)
tr->dir = debugfs_create_automount("tracing", NULL,
trace_automount, NULL);

- return NULL;
+ return 0;
}

extern struct trace_eval_map *__start_ftrace_eval_maps[];
@@ -9047,48 +9047,48 @@ static struct notifier_block trace_module_nb = {

static __init int tracer_init_tracefs(void)
{
- struct dentry *d_tracer;
+ int ret;

trace_access_lock_init();

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

event_trace_init();

- init_tracer_tracefs(&global_trace, d_tracer);
- ftrace_init_tracefs_toplevel(&global_trace, d_tracer);
+ init_tracer_tracefs(&global_trace, NULL);
+ ftrace_init_tracefs_toplevel(&global_trace, NULL);

- trace_create_file("tracing_thresh", 0644, d_tracer,
+ trace_create_file("tracing_thresh", 0644, NULL,
&global_trace, &tracing_thresh_fops);

- trace_create_file("README", 0444, d_tracer,
+ trace_create_file("README", 0444, NULL,
NULL, &tracing_readme_fops);

- trace_create_file("saved_cmdlines", 0444, d_tracer,
+ trace_create_file("saved_cmdlines", 0444, NULL,
NULL, &tracing_saved_cmdlines_fops);

- trace_create_file("saved_cmdlines_size", 0644, d_tracer,
+ trace_create_file("saved_cmdlines_size", 0644, NULL,
NULL, &tracing_saved_cmdlines_size_fops);

- trace_create_file("saved_tgids", 0444, d_tracer,
+ trace_create_file("saved_tgids", 0444, NULL,
NULL, &tracing_saved_tgids_fops);

trace_eval_init();

- trace_create_eval_file(d_tracer);
+ trace_create_eval_file(NULL);

#ifdef CONFIG_MODULES
register_module_notifier(&trace_module_nb);
#endif

#ifdef CONFIG_DYNAMIC_FTRACE
- trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
+ trace_create_file("dyn_ftrace_total_info", 0444, NULL,
NULL, &tracing_dyn_info_fops);
#endif

- create_trace_instances(d_tracer);
+ create_trace_instances(NULL);

update_tracer_options(&global_trace);

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index def769df5bf1..afcef31ae76d 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -734,7 +734,7 @@ struct dentry *trace_create_file(const char *name,
void *data,
const struct file_operations *fops);

-struct dentry *tracing_init_dentry(void);
+int tracing_init_dentry(void);

struct ring_buffer_event;

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 9f2e8520b748..9442a9bb080e 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -206,14 +206,14 @@ static const struct file_operations dynamic_events_ops = {
/* Make a tracefs interface for controlling dynamic events */
static __init int init_dynamic_event(void)
{
- struct dentry *d_tracer;
struct dentry *entry;
+ int ret;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- entry = tracefs_create_file("dynamic_events", 0644, d_tracer,
+ entry = tracefs_create_file("dynamic_events", 0644, NULL,
NULL, &dynamic_events_ops);

/* Event list interface */
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index c6cca0d1d584..f86a2aa0bccd 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -1757,7 +1757,6 @@ static const struct file_operations synth_events_fops = {
static __init int trace_events_synth_init(void)
{
struct dentry *entry = NULL;
- struct dentry *d_tracer;
int err = 0;

err = dyn_event_register(&synth_event_ops);
@@ -1766,13 +1765,11 @@ static __init int trace_events_synth_init(void)
return err;
}

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer)) {
- err = PTR_ERR(d_tracer);
+ err = tracing_init_dentry();
+ if (err)
goto err;
- }

- entry = tracefs_create_file("synthetic_events", 0644, d_tracer,
+ entry = tracefs_create_file("synthetic_events", 0644, NULL,
NULL, &synth_events_fops);
if (!entry) {
err = -ENODEV;
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4a9c49c08ec9..60d66278aa0d 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1336,13 +1336,13 @@ static const struct file_operations graph_depth_fops = {

static __init int init_graph_tracefs(void)
{
- struct dentry *d_tracer;
+ int ret;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- trace_create_file("max_graph_depth", 0644, d_tracer,
+ trace_create_file("max_graph_depth", 0644, NULL,
NULL, &graph_depth_fops);

return 0;
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index e2be7bb7ef7e..4ddbad511b6d 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -538,14 +538,14 @@ static const struct file_operations window_fops = {
*/
static int init_tracefs(void)
{
- struct dentry *d_tracer;
+ int ret;
struct dentry *top_dir;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return -ENOMEM;

- top_dir = tracefs_create_dir("hwlat_detector", d_tracer);
+ top_dir = tracefs_create_dir("hwlat_detector", NULL);
if (!top_dir)
return -ENOMEM;

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ea8d0b094f1b..51de3a9ffd1c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1901,14 +1901,14 @@ subsys_initcall(init_kprobe_trace_early);
/* Make a tracefs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{
- struct dentry *d_tracer;
+ int ret;
struct dentry *entry;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
+ entry = tracefs_create_file("kprobe_events", 0644, NULL,
NULL, &kprobe_events_ops);

/* Event list interface */
@@ -1916,7 +1916,7 @@ static __init int init_kprobe_trace(void)
pr_warn("Could not create tracefs 'kprobe_events' entry\n");

/* Profile interface */
- entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
+ entry = tracefs_create_file("kprobe_profile", 0444, NULL,
NULL, &kprobe_profile_ops);

if (!entry)
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index d4e31e969206..71b2e0fdc3e0 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -367,13 +367,13 @@ static const struct file_operations ftrace_formats_fops = {

static __init int init_trace_printk_function_export(void)
{
- struct dentry *d_tracer;
+ int ret;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- trace_create_file("printk_formats", 0444, d_tracer,
+ trace_create_file("printk_formats", 0444, NULL,
NULL, &ftrace_formats_fops);

return 0;
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index c557f42a9397..67711269184b 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -555,20 +555,20 @@ __setup("stacktrace", enable_stacktrace);

static __init int stack_trace_init(void)
{
- struct dentry *d_tracer;
+ int ret;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- trace_create_file("stack_max_size", 0644, d_tracer,
+ trace_create_file("stack_max_size", 0644, NULL,
&stack_trace_max_size, &stack_max_size_fops);

- trace_create_file("stack_trace", 0444, d_tracer,
+ trace_create_file("stack_trace", 0444, NULL,
NULL, &stack_trace_fops);

#ifdef CONFIG_DYNAMIC_FTRACE
- trace_create_file("stack_trace_filter", 0644, d_tracer,
+ trace_create_file("stack_trace_filter", 0644, NULL,
&trace_ops, &stack_trace_filter_fops);
#endif

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index d1fa19773cc8..8d141c3825a9 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -276,13 +276,13 @@ static const struct file_operations tracing_stat_fops = {

static int tracing_stat_init(void)
{
- struct dentry *d_tracing;
+ int ret;

- d_tracing = tracing_init_dentry();
- if (IS_ERR(d_tracing))
+ ret = tracing_init_dentry();
+ if (ret)
return -ENODEV;

- stat_dir = tracefs_create_dir("trace_stat", d_tracing);
+ stat_dir = tracefs_create_dir("trace_stat", NULL);
if (!stat_dir) {
pr_warn("Could not create tracefs 'trace_stat' entry\n");
return -ENOMEM;
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 2a8e8e9c1c75..502dbecf6c9f 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -1626,21 +1626,20 @@ void destroy_local_trace_uprobe(struct trace_event_call *event_call)
/* Make a trace interface for controling probe points */
static __init int init_uprobe_trace(void)
{
- struct dentry *d_tracer;
int ret;

ret = dyn_event_register(&trace_uprobe_ops);
if (ret)
return ret;

- d_tracer = tracing_init_dentry();
- if (IS_ERR(d_tracer))
+ ret = tracing_init_dentry();
+ if (ret)
return 0;

- trace_create_file("uprobe_events", 0644, d_tracer,
+ trace_create_file("uprobe_events", 0644, NULL,
NULL, &uprobe_events_ops);
/* Profile interface */
- trace_create_file("uprobe_profile", 0444, d_tracer,
+ trace_create_file("uprobe_profile", 0444, NULL,
NULL, &uprobe_profile_ops);
return 0;
}
--
2.20.1 (Apple Git-117)

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