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Message-ID: <alpine.DEB.2.00.0903231413270.3578@gandalf.stny.rr.com>
Date: Mon, 23 Mar 2009 14:24:21 -0400 (EDT)
From: Steven Rostedt <rostedt@...dmis.org>
To: Tom Zanussi <tzanussi@...il.com>
cc: linux-kernel <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>,
Frédéric Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 4/4] tracing: add per-subsystem filtering
On Sun, 22 Mar 2009, Tom Zanussi wrote:
>
> +struct event_subsystem {
> + struct list_head list;
> + const char *name;
> + struct dentry *entry;
> + struct filter_pred **preds;
> +};
> +
> +#define events_for_each(event) \
> + for (event = __start_ftrace_events; \
> + (unsigned long)event < (unsigned long)__stop_ftrace_events; \
> + event++)
> +
> #define MAX_FILTER_PRED 8
>
> struct filter_pred;
> @@ -832,6 +844,9 @@ extern int filter_add_pred(struct ftrace_event_call *call,
> struct filter_pred *pred);
> extern void filter_free_preds(struct ftrace_event_call *call);
> extern int filter_match_preds(struct ftrace_event_call *call, void *rec);
> +extern void filter_free_subsystem_preds(struct event_subsystem *system);
> +extern int filter_add_subsystem_pred(struct event_subsystem *system,
> + struct filter_pred *pred);
>
> void event_trace_printk(unsigned long ip, const char *fmt, ...);
> extern struct ftrace_event_call __start_ftrace_events[];
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 97470c4..97d4daa 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -524,6 +524,71 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
> return cnt;
> }
>
> +static ssize_t
> +subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
> + loff_t *ppos)
> +{
> + struct event_subsystem *system = filp->private_data;
> + struct trace_seq *s;
Again, trace_seq is not used, might as well use your own buffer.
> + int r;
> +
> + if (*ppos)
> + return 0;
> +
> + s = kmalloc(sizeof(*s), GFP_KERNEL);
> + if (!s)
> + return -ENOMEM;
> +
> + trace_seq_init(s);
> +
> + r = filter_print_preds(system->preds, s->buffer);
> + r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, r);
> +
> + kfree(s);
> +
> + return r;
> +}
> +
> +static ssize_t
> +subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
> + loff_t *ppos)
> +{
> + struct event_subsystem *system = filp->private_data;
> + char buf[64], *pbuf = buf;
> + struct filter_pred *pred;
> + int err;
> +
> + if (cnt >= sizeof(buf))
> + return -EINVAL;
> +
> + if (copy_from_user(&buf, ubuf, cnt))
> + return -EFAULT;
> +
> + pred = kzalloc(sizeof(*pred), GFP_KERNEL);
> + if (!pred)
> + return -ENOMEM;
> +
> + err = filter_parse(&pbuf, pred);
> + if (err < 0) {
> + filter_free_pred(pred);
> + return err;
> + }
> +
> + if (pred->clear) {
> + filter_free_subsystem_preds(system);
is "system" correct here?
> + return cnt;
> + }
> +
> + if (filter_add_subsystem_pred(system, pred)) {
> + filter_free_pred(pred);
> + return -EINVAL;
> + }
> +
> + *ppos += cnt;
> +
> + return cnt;
> +}
> +
> static const struct seq_operations show_event_seq_ops = {
> .start = t_start,
> .next = t_next,
> @@ -575,6 +640,12 @@ static const struct file_operations ftrace_event_filter_fops = {
> .write = event_filter_write,
> };
>
> +static const struct file_operations ftrace_subsystem_filter_fops = {
> + .open = tracing_open_generic,
> + .read = subsystem_filter_read,
> + .write = subsystem_filter_write,
> +};
> +
> static struct dentry *event_trace_events_dir(void)
> {
> static struct dentry *d_tracer;
> @@ -595,18 +666,13 @@ static struct dentry *event_trace_events_dir(void)
> return d_events;
> }
>
> -struct event_subsystem {
> - struct list_head list;
> - const char *name;
> - struct dentry *entry;
> -};
> -
> static LIST_HEAD(event_subsystems);
>
> static struct dentry *
> event_subsystem_dir(const char *name, struct dentry *d_events)
> {
> struct event_subsystem *system;
> + struct dentry *entry;
>
> /* First see if we did not already create this dir */
> list_for_each_entry(system, &event_subsystems, list) {
> @@ -633,6 +699,14 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
> system->name = name;
> list_add(&system->list, &event_subsystems);
>
> + system->preds = NULL;
> +
> + entry = debugfs_create_file("filter", 0444, system->entry, system,
> + &ftrace_subsystem_filter_fops);
> + if (!entry)
> + pr_warning("Could not create debugfs "
> + "'%s/filter' entry\n", name);
> +
> return system->entry;
> }
>
> diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
> index 8e8c5fa..1ab20ce 100644
> --- a/kernel/trace/trace_events_filter.c
> +++ b/kernel/trace/trace_events_filter.c
> @@ -181,6 +181,27 @@ void filter_free_preds(struct ftrace_event_call *call)
> }
> }
>
> +void filter_free_subsystem_preds(struct event_subsystem *system)
> +{
> + struct ftrace_event_call *call = __start_ftrace_events;
> + int i;
> +
> + if (system->preds) {
> + for (i = 0; i < MAX_FILTER_PRED; i++)
> + filter_free_pred(system->preds[i]);
> + kfree(system->preds);
> + system->preds = NULL;
> + }
> +
> + events_for_each(call) {
> + if (!call->name || !call->regfunc)
> + continue;
> +
> + if (!strcmp(call->system, system->name))
> + filter_free_preds(call);
> + }
> +}
> +
> static int __filter_add_pred(struct ftrace_event_call *call,
> struct filter_pred *pred)
> {
> @@ -250,6 +271,65 @@ int filter_add_pred(struct ftrace_event_call *call, struct filter_pred *pred)
> return __filter_add_pred(call, pred);
> }
>
> +static struct filter_pred *copy_pred(struct filter_pred *pred)
> +{
> + struct filter_pred *new_pred = kmalloc(sizeof(*pred), GFP_KERNEL);
> + if (!new_pred)
> + return NULL;
> +
> + memcpy(new_pred, pred, sizeof(*pred));
> + if (pred->str_val) {
> + new_pred->str_val = kstrdup(pred->str_val, GFP_KERNEL);
> + new_pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
> + if (!new_pred->str_val) {
> + kfree(new_pred);
Shouldn't there be a check for field_name too?
-- Steve
> + return NULL;
> + }
> + }
> +
> + return new_pred;
> +}
> +
--
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