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Subject[RFC][PATCH 09/17 v2] tracing: Show the mapped enums in enum_map file
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Add a enum_map file in the tracing directory to see what enums have been
saved to convert in the print fmt files.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 107 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c9a714a42b7b..f2e63d0bf45e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -123,7 +123,7 @@ enum ftrace_dump_mode ftrace_dump_on_oops;
/* When set, tracing will stop when a WARN*() is hit */
int __disable_trace_on_warning;

-/* Map of enums to their values */
+/* Map of enums to their values, for "enum_map" file */
struct trace_enum_map_head {
struct module *mod;
unsigned long length;
@@ -136,10 +136,12 @@ struct trace_enum_map_tail {
* "end" is first and points to NULL as it must be different
* than "mod" or "enum_string"
*/
- const char *end; /* points to NULL */
union trace_enum_map_item *next;
+ const char *end; /* points to NULL */
};

+static DEFINE_MUTEX(trace_enum_mutex);
+
/*
* The trace_enum_maps are saved in an array with two extra elements,
* one at the beginning, and one at the end. The beginning item contains
@@ -3940,6 +3942,97 @@ static const struct file_operations tracing_saved_cmdlines_size_fops = {
.write = tracing_saved_cmdlines_size_write,
};

+static union trace_enum_map_item *
+update_enum_map(union trace_enum_map_item *ptr)
+{
+ if (!ptr->map.enum_string) {
+ if (ptr->tail.next) {
+ ptr = ptr->tail.next;
+ /* Set ptr to the next real item (skip head) */
+ ptr++;
+ } else
+ return NULL;
+ }
+ return ptr;
+}
+
+static void *enum_map_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ union trace_enum_map_item *ptr = v;
+
+ /*
+ * Paranoid! If ptr points to end, we don't want to increment past it.
+ * This really should never happen.
+ */
+ ptr = update_enum_map(ptr);
+ if (WARN_ON_ONCE(!ptr))
+ return NULL;
+
+ ptr++;
+
+ (*pos)++;
+
+ ptr = update_enum_map(ptr);
+
+ return ptr;
+}
+
+static void *enum_map_start(struct seq_file *m, loff_t *pos)
+{
+ union trace_enum_map_item *v;
+ loff_t l = 0;
+
+ mutex_lock(&trace_enum_mutex);
+
+ v = trace_enum_maps;
+ if (v)
+ v++;
+
+ while (v && l < *pos) {
+ v = enum_map_next(m, v, &l);
+ }
+
+ return v;
+}
+
+static void enum_map_stop(struct seq_file *m, void *v)
+{
+ mutex_unlock(&trace_enum_mutex);
+}
+
+static int enum_map_show(struct seq_file *m, void *v)
+{
+ union trace_enum_map_item *ptr = v;
+
+ seq_printf(m, "%s %ld (%s)\n",
+ ptr->map.enum_string, ptr->map.enum_value,
+ ptr->map.system);
+
+ return 0;
+}
+
+static const struct seq_operations tracing_enum_map_seq_ops = {
+ .start = enum_map_start,
+ .next = enum_map_next,
+ .stop = enum_map_stop,
+ .show = enum_map_show,
+};
+
+static int tracing_enum_map_open(struct inode *inode, struct file *filp)
+{
+ if (tracing_disabled)
+ return -ENODEV;
+
+ return seq_open(filp, &tracing_enum_map_seq_ops);
+}
+
+static const struct file_operations tracing_enum_map_fops = {
+ .open = tracing_enum_map_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
static inline union trace_enum_map_item *
trace_enum_jmp_to_tail(union trace_enum_map_item *ptr)
{
@@ -3971,6 +4064,8 @@ static void trace_insert_enum_map(struct module *mod,
return;
}

+ mutex_lock(&trace_enum_mutex);
+
if (!trace_enum_maps)
trace_enum_maps = map_array;
else {
@@ -3996,6 +4091,8 @@ static void trace_insert_enum_map(struct module *mod,

/* Pass in the start of the array (-len) */
trace_event_enum_update(&map_array[-len].map, len);
+
+ mutex_unlock(&trace_enum_mutex);
}

static ssize_t
@@ -6667,6 +6764,8 @@ static void trace_module_remove_enums(struct module *mod)
if (!mod->num_trace_enums)
return;

+ mutex_lock(&trace_enum_mutex);
+
map = trace_enum_maps;

while (map) {
@@ -6677,10 +6776,12 @@ static void trace_module_remove_enums(struct module *mod)
map = map->tail.next;
}
if (!map)
- return;
+ goto out;

*last = trace_enum_jmp_to_tail(map)->tail.next;
kfree(map);
+ out:
+ mutex_unlock(&trace_enum_mutex);
}

static int trace_module_notify(struct notifier_block *self,
@@ -6732,6 +6833,9 @@ static __init int tracer_init_debugfs(void)

trace_enum_init();

+ trace_create_file("enum_map", 0444, d_tracer,
+ NULL, &tracing_enum_map_fops);
+
#ifdef CONFIG_MODULES
register_module_notifier(&trace_module_nb);
#endif
--
2.1.4



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