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Subject[PATCH 2/5] tracing: add tracer dependent options to options directory
From: Steven Rostedt <srostedt@redhat.com>

This patch adds the tracer dependent options dynamically to the
options directory when the tracer is activated. These options are
removed when the tracer is deactivated.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/trace.c | 174 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 173 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 40e983e..485c6e7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2275,8 +2275,17 @@ int tracer_init(struct tracer *t, struct trace_array *tr)
return t->init(tr);
}

+struct trace_option_dentry;
+
+static struct trace_option_dentry *
+create_trace_option_files(struct tracer *tracer);
+
+static void
+destroy_trace_option_files(struct trace_option_dentry *topts);
+
static int tracing_set_tracer(const char *buf)
{
+ static struct trace_option_dentry *topts;
struct trace_array *tr = &global_trace;
struct tracer *t;
int ret = 0;
@@ -2297,7 +2306,12 @@ static int tracing_set_tracer(const char *buf)
if (current_trace && current_trace->reset)
current_trace->reset(tr);

+ destroy_trace_option_files(topts);
+
current_trace = t;
+
+ topts = create_trace_option_files(current_trace);
+
if (t->init) {
ret = tracer_init(t, tr);
if (ret)
@@ -3093,6 +3107,95 @@ static void tracing_init_debugfs_percpu(long cpu)
#include "trace_selftest.c"
#endif

+struct trace_option_dentry {
+ struct tracer_opt *opt;
+ struct tracer_flags *flags;
+ struct dentry *entry;
+};
+
+static ssize_t
+trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ struct trace_option_dentry *topt = filp->private_data;
+ char *buf;
+
+ if (topt->flags->val & topt->opt->bit)
+ buf = "1\n";
+ else
+ buf = "0\n";
+
+ return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
+}
+
+static ssize_t
+trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ struct trace_option_dentry *topt = filp->private_data;
+ unsigned long val;
+ char buf[64];
+ int ret;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ ret = strict_strtoul(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+
+ ret = 0;
+ switch (val) {
+ case 0:
+ /* do nothing if already cleared */
+ if (!(topt->flags->val & topt->opt->bit))
+ break;
+
+ mutex_lock(&trace_types_lock);
+ if (current_trace->set_flag)
+ ret = current_trace->set_flag(topt->flags->val,
+ topt->opt->bit, 0);
+ mutex_unlock(&trace_types_lock);
+ if (ret)
+ return ret;
+ topt->flags->val &= ~topt->opt->bit;
+ break;
+ case 1:
+ /* do nothing if already set */
+ if (topt->flags->val & topt->opt->bit)
+ break;
+
+ mutex_lock(&trace_types_lock);
+ if (current_trace->set_flag)
+ ret = current_trace->set_flag(topt->flags->val,
+ topt->opt->bit, 1);
+ mutex_unlock(&trace_types_lock);
+ if (ret)
+ return ret;
+ topt->flags->val |= topt->opt->bit;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ *ppos += cnt;
+
+ return cnt;
+}
+
+
+static const struct file_operations trace_options_fops = {
+ .open = tracing_open_generic,
+ .read = trace_options_read,
+ .write = trace_options_write,
+};
+
static ssize_t
trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
@@ -3146,7 +3249,6 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
return cnt;
}

-
static const struct file_operations trace_options_core_fops = {
.open = tracing_open_generic,
.read = trace_options_core_read,
@@ -3174,6 +3276,76 @@ static struct dentry *trace_options_init_dentry(void)
return t_options;
}

+static void
+create_trace_option_file(struct trace_option_dentry *topt,
+ struct tracer_flags *flags,
+ struct tracer_opt *opt)
+{
+ struct dentry *t_options;
+ struct dentry *entry;
+
+ t_options = trace_options_init_dentry();
+ if (!t_options)
+ return;
+
+ topt->flags = flags;
+ topt->opt = opt;
+
+ entry = debugfs_create_file(opt->name, 0644, t_options, topt,
+ &trace_options_fops);
+
+ topt->entry = entry;
+
+}
+
+static struct trace_option_dentry *
+create_trace_option_files(struct tracer *tracer)
+{
+ struct trace_option_dentry *topts;
+ struct tracer_flags *flags;
+ struct tracer_opt *opts;
+ int cnt;
+
+ if (!tracer)
+ return NULL;
+
+ flags = tracer->flags;
+
+ if (!flags || !flags->opts)
+ return NULL;
+
+ opts = flags->opts;
+
+ for (cnt = 0; opts[cnt].name; cnt++)
+ ;
+
+ topts = kzalloc(sizeof(*topts) * (cnt + 1), GFP_KERNEL);
+ if (!topts)
+ return NULL;
+
+ for (cnt = 0; opts[cnt].name; cnt++)
+ create_trace_option_file(&topts[cnt], flags,
+ &opts[cnt]);
+
+ return topts;
+}
+
+static void
+destroy_trace_option_files(struct trace_option_dentry *topts)
+{
+ int cnt;
+
+ if (!topts)
+ return;
+
+ for (cnt = 0; topts[cnt].opt; cnt++) {
+ if (topts[cnt].entry)
+ debugfs_remove(topts[cnt].entry);
+ }
+
+ kfree(topts);
+}
+
static struct dentry *
create_trace_option_core_file(const char *option, long index)
{
--
1.5.6.5
--


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