linux/kernel/trace/trace_events_trigger.c
Steven Rostedt (Red Hat) 561a4fe851 tracing: Use rcu_dereference_sched() for trace event triggers
As trace event triggers are now part of the mainline kernel, I added
my trace event trigger tests to my test suite I run on all my kernels.
Now these tests get run under different config options, and one of
those options is CONFIG_PROVE_RCU, which checks under lockdep that
the rcu locking primitives are being used correctly. This triggered
the following splat:

===============================
[ INFO: suspicious RCU usage. ]
3.15.0-rc2-test+ #11 Not tainted
-------------------------------
kernel/trace/trace_events_trigger.c:80 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
4 locks held by swapper/1/0:
 #0:  ((&(&j_cdbs->work)->timer)){..-...}, at: [<ffffffff8104d2cc>] call_timer_fn+0x5/0x1be
 #1:  (&(&pool->lock)->rlock){-.-...}, at: [<ffffffff81059856>] __queue_work+0x140/0x283
 #2:  (&p->pi_lock){-.-.-.}, at: [<ffffffff8106e961>] try_to_wake_up+0x2e/0x1e8
 #3:  (&rq->lock){-.-.-.}, at: [<ffffffff8106ead3>] try_to_wake_up+0x1a0/0x1e8

stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.15.0-rc2-test+ #11
Hardware name:                  /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006
 0000000000000001 ffff88007e083b98 ffffffff819f53a5 0000000000000006
 ffff88007b0942c0 ffff88007e083bc8 ffffffff81081307 ffff88007ad96d20
 0000000000000000 ffff88007af2d840 ffff88007b2e701c ffff88007e083c18
Call Trace:
 <IRQ>  [<ffffffff819f53a5>] dump_stack+0x4f/0x7c
 [<ffffffff81081307>] lockdep_rcu_suspicious+0x107/0x110
 [<ffffffff810ee51c>] event_triggers_call+0x99/0x108
 [<ffffffff810e8174>] ftrace_event_buffer_commit+0x42/0xa4
 [<ffffffff8106aadc>] ftrace_raw_event_sched_wakeup_template+0x71/0x7c
 [<ffffffff8106bcbf>] ttwu_do_wakeup+0x7f/0xff
 [<ffffffff8106bd9b>] ttwu_do_activate.constprop.126+0x5c/0x61
 [<ffffffff8106eadf>] try_to_wake_up+0x1ac/0x1e8
 [<ffffffff8106eb77>] wake_up_process+0x36/0x3b
 [<ffffffff810575cc>] wake_up_worker+0x24/0x26
 [<ffffffff810578bc>] insert_work+0x5c/0x65
 [<ffffffff81059982>] __queue_work+0x26c/0x283
 [<ffffffff81059999>] ? __queue_work+0x283/0x283
 [<ffffffff810599b7>] delayed_work_timer_fn+0x1e/0x20
 [<ffffffff8104d3a6>] call_timer_fn+0xdf/0x1be^M
 [<ffffffff8104d2cc>] ? call_timer_fn+0x5/0x1be
 [<ffffffff81059999>] ? __queue_work+0x283/0x283
 [<ffffffff8104d823>] run_timer_softirq+0x1a4/0x22f^M
 [<ffffffff8104696d>] __do_softirq+0x17b/0x31b^M
 [<ffffffff81046d03>] irq_exit+0x42/0x97
 [<ffffffff81a08db6>] smp_apic_timer_interrupt+0x37/0x44
 [<ffffffff81a07a2f>] apic_timer_interrupt+0x6f/0x80
 <EOI>  [<ffffffff8100a5d8>] ? default_idle+0x21/0x32
 [<ffffffff8100a5d6>] ? default_idle+0x1f/0x32
 [<ffffffff8100ac10>] arch_cpu_idle+0xf/0x11
 [<ffffffff8107b3a4>] cpu_startup_entry+0x1a3/0x213
 [<ffffffff8102a23c>] start_secondary+0x212/0x219

The cause is that the triggers are protected by rcu_read_lock_sched() but
the data is dereferenced with rcu_dereference() which expects it to
be protected with rcu_read_lock(). The proper reference should be
rcu_dereference_sched().

Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-05-02 23:12:42 -04:00

1438 lines
35 KiB
C

/*
* trace_events_trigger - trace event triggers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
*/
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include "trace.h"
static LIST_HEAD(trigger_commands);
static DEFINE_MUTEX(trigger_cmd_mutex);
static void
trigger_data_free(struct event_trigger_data *data)
{
if (data->cmd_ops->set_filter)
data->cmd_ops->set_filter(NULL, data, NULL);
synchronize_sched(); /* make sure current triggers exit before free */
kfree(data);
}
/**
* event_triggers_call - Call triggers associated with a trace event
* @file: The ftrace_event_file associated with the event
* @rec: The trace entry for the event, NULL for unconditional invocation
*
* For each trigger associated with an event, invoke the trigger
* function registered with the associated trigger command. If rec is
* non-NULL, it means that the trigger requires further processing and
* shouldn't be unconditionally invoked. If rec is non-NULL and the
* trigger has a filter associated with it, rec will checked against
* the filter and if the record matches the trigger will be invoked.
* If the trigger is a 'post_trigger', meaning it shouldn't be invoked
* in any case until the current event is written, the trigger
* function isn't invoked but the bit associated with the deferred
* trigger is set in the return value.
*
* Returns an enum event_trigger_type value containing a set bit for
* any trigger that should be deferred, ETT_NONE if nothing to defer.
*
* Called from tracepoint handlers (with rcu_read_lock_sched() held).
*
* Return: an enum event_trigger_type value containing a set bit for
* any trigger that should be deferred, ETT_NONE if nothing to defer.
*/
enum event_trigger_type
event_triggers_call(struct ftrace_event_file *file, void *rec)
{
struct event_trigger_data *data;
enum event_trigger_type tt = ETT_NONE;
struct event_filter *filter;
if (list_empty(&file->triggers))
return tt;
list_for_each_entry_rcu(data, &file->triggers, list) {
if (!rec) {
data->ops->func(data);
continue;
}
filter = rcu_dereference_sched(data->filter);
if (filter && !filter_match_preds(filter, rec))
continue;
if (data->cmd_ops->post_trigger) {
tt |= data->cmd_ops->trigger_type;
continue;
}
data->ops->func(data);
}
return tt;
}
EXPORT_SYMBOL_GPL(event_triggers_call);
/**
* event_triggers_post_call - Call 'post_triggers' for a trace event
* @file: The ftrace_event_file associated with the event
* @tt: enum event_trigger_type containing a set bit for each trigger to invoke
*
* For each trigger associated with an event, invoke the trigger
* function registered with the associated trigger command, if the
* corresponding bit is set in the tt enum passed into this function.
* See @event_triggers_call for details on how those bits are set.
*
* Called from tracepoint handlers (with rcu_read_lock_sched() held).
*/
void
event_triggers_post_call(struct ftrace_event_file *file,
enum event_trigger_type tt)
{
struct event_trigger_data *data;
list_for_each_entry_rcu(data, &file->triggers, list) {
if (data->cmd_ops->trigger_type & tt)
data->ops->func(data);
}
}
EXPORT_SYMBOL_GPL(event_triggers_post_call);
#define SHOW_AVAILABLE_TRIGGERS (void *)(1UL)
static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
{
struct ftrace_event_file *event_file = event_file_data(m->private);
if (t == SHOW_AVAILABLE_TRIGGERS)
return NULL;
return seq_list_next(t, &event_file->triggers, pos);
}
static void *trigger_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_event_file *event_file;
/* ->stop() is called even if ->start() fails */
mutex_lock(&event_mutex);
event_file = event_file_data(m->private);
if (unlikely(!event_file))
return ERR_PTR(-ENODEV);
if (list_empty(&event_file->triggers))
return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
return seq_list_start(&event_file->triggers, *pos);
}
static void trigger_stop(struct seq_file *m, void *t)
{
mutex_unlock(&event_mutex);
}
static int trigger_show(struct seq_file *m, void *v)
{
struct event_trigger_data *data;
struct event_command *p;
if (v == SHOW_AVAILABLE_TRIGGERS) {
seq_puts(m, "# Available triggers:\n");
seq_putc(m, '#');
mutex_lock(&trigger_cmd_mutex);
list_for_each_entry_reverse(p, &trigger_commands, list)
seq_printf(m, " %s", p->name);
seq_putc(m, '\n');
mutex_unlock(&trigger_cmd_mutex);
return 0;
}
data = list_entry(v, struct event_trigger_data, list);
data->ops->print(m, data->ops, data);
return 0;
}
static const struct seq_operations event_triggers_seq_ops = {
.start = trigger_start,
.next = trigger_next,
.stop = trigger_stop,
.show = trigger_show,
};
static int event_trigger_regex_open(struct inode *inode, struct file *file)
{
int ret = 0;
mutex_lock(&event_mutex);
if (unlikely(!event_file_data(file))) {
mutex_unlock(&event_mutex);
return -ENODEV;
}
if (file->f_mode & FMODE_READ) {
ret = seq_open(file, &event_triggers_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = file;
}
}
mutex_unlock(&event_mutex);
return ret;
}
static int trigger_process_regex(struct ftrace_event_file *file, char *buff)
{
char *command, *next = buff;
struct event_command *p;
int ret = -EINVAL;
command = strsep(&next, ": \t");
command = (command[0] != '!') ? command : command + 1;
mutex_lock(&trigger_cmd_mutex);
list_for_each_entry(p, &trigger_commands, list) {
if (strcmp(p->name, command) == 0) {
ret = p->func(p, file, buff, command, next);
goto out_unlock;
}
}
out_unlock:
mutex_unlock(&trigger_cmd_mutex);
return ret;
}
static ssize_t event_trigger_regex_write(struct file *file,
const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct ftrace_event_file *event_file;
ssize_t ret;
char *buf;
if (!cnt)
return 0;
if (cnt >= PAGE_SIZE)
return -EINVAL;
buf = (char *)__get_free_page(GFP_TEMPORARY);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, ubuf, cnt)) {
free_page((unsigned long)buf);
return -EFAULT;
}
buf[cnt] = '\0';
strim(buf);
mutex_lock(&event_mutex);
event_file = event_file_data(file);
if (unlikely(!event_file)) {
mutex_unlock(&event_mutex);
free_page((unsigned long)buf);
return -ENODEV;
}
ret = trigger_process_regex(event_file, buf);
mutex_unlock(&event_mutex);
free_page((unsigned long)buf);
if (ret < 0)
goto out;
*ppos += cnt;
ret = cnt;
out:
return ret;
}
static int event_trigger_regex_release(struct inode *inode, struct file *file)
{
mutex_lock(&event_mutex);
if (file->f_mode & FMODE_READ)
seq_release(inode, file);
mutex_unlock(&event_mutex);
return 0;
}
static ssize_t
event_trigger_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return event_trigger_regex_write(filp, ubuf, cnt, ppos);
}
static int
event_trigger_open(struct inode *inode, struct file *filp)
{
return event_trigger_regex_open(inode, filp);
}
static int
event_trigger_release(struct inode *inode, struct file *file)
{
return event_trigger_regex_release(inode, file);
}
const struct file_operations event_trigger_fops = {
.open = event_trigger_open,
.read = seq_read,
.write = event_trigger_write,
.llseek = tracing_lseek,
.release = event_trigger_release,
};
/*
* Currently we only register event commands from __init, so mark this
* __init too.
*/
static __init int register_event_command(struct event_command *cmd)
{
struct event_command *p;
int ret = 0;
mutex_lock(&trigger_cmd_mutex);
list_for_each_entry(p, &trigger_commands, list) {
if (strcmp(cmd->name, p->name) == 0) {
ret = -EBUSY;
goto out_unlock;
}
}
list_add(&cmd->list, &trigger_commands);
out_unlock:
mutex_unlock(&trigger_cmd_mutex);
return ret;
}
/*
* Currently we only unregister event commands from __init, so mark
* this __init too.
*/
static __init int unregister_event_command(struct event_command *cmd)
{
struct event_command *p, *n;
int ret = -ENODEV;
mutex_lock(&trigger_cmd_mutex);
list_for_each_entry_safe(p, n, &trigger_commands, list) {
if (strcmp(cmd->name, p->name) == 0) {
ret = 0;
list_del_init(&p->list);
goto out_unlock;
}
}
out_unlock:
mutex_unlock(&trigger_cmd_mutex);
return ret;
}
/**
* event_trigger_print - Generic event_trigger_ops @print implementation
* @name: The name of the event trigger
* @m: The seq_file being printed to
* @data: Trigger-specific data
* @filter_str: filter_str to print, if present
*
* Common implementation for event triggers to print themselves.
*
* Usually wrapped by a function that simply sets the @name of the
* trigger command and then invokes this.
*
* Return: 0 on success, errno otherwise
*/
static int
event_trigger_print(const char *name, struct seq_file *m,
void *data, char *filter_str)
{
long count = (long)data;
seq_printf(m, "%s", name);
if (count == -1)
seq_puts(m, ":unlimited");
else
seq_printf(m, ":count=%ld", count);
if (filter_str)
seq_printf(m, " if %s\n", filter_str);
else
seq_puts(m, "\n");
return 0;
}
/**
* event_trigger_init - Generic event_trigger_ops @init implementation
* @ops: The trigger ops associated with the trigger
* @data: Trigger-specific data
*
* Common implementation of event trigger initialization.
*
* Usually used directly as the @init method in event trigger
* implementations.
*
* Return: 0 on success, errno otherwise
*/
static int
event_trigger_init(struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
data->ref++;
return 0;
}
/**
* event_trigger_free - Generic event_trigger_ops @free implementation
* @ops: The trigger ops associated with the trigger
* @data: Trigger-specific data
*
* Common implementation of event trigger de-initialization.
*
* Usually used directly as the @free method in event trigger
* implementations.
*/
static void
event_trigger_free(struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
if (WARN_ON_ONCE(data->ref <= 0))
return;
data->ref--;
if (!data->ref)
trigger_data_free(data);
}
static int trace_event_trigger_enable_disable(struct ftrace_event_file *file,
int trigger_enable)
{
int ret = 0;
if (trigger_enable) {
if (atomic_inc_return(&file->tm_ref) > 1)
return ret;
set_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &file->flags);
ret = trace_event_enable_disable(file, 1, 1);
} else {
if (atomic_dec_return(&file->tm_ref) > 0)
return ret;
clear_bit(FTRACE_EVENT_FL_TRIGGER_MODE_BIT, &file->flags);
ret = trace_event_enable_disable(file, 0, 1);
}
return ret;
}
/**
* clear_event_triggers - Clear all triggers associated with a trace array
* @tr: The trace array to clear
*
* For each trigger, the triggering event has its tm_ref decremented
* via trace_event_trigger_enable_disable(), and any associated event
* (in the case of enable/disable_event triggers) will have its sm_ref
* decremented via free()->trace_event_enable_disable(). That
* combination effectively reverses the soft-mode/trigger state added
* by trigger registration.
*
* Must be called with event_mutex held.
*/
void
clear_event_triggers(struct trace_array *tr)
{
struct ftrace_event_file *file;
list_for_each_entry(file, &tr->events, list) {
struct event_trigger_data *data;
list_for_each_entry_rcu(data, &file->triggers, list) {
trace_event_trigger_enable_disable(file, 0);
if (data->ops->free)
data->ops->free(data->ops, data);
}
}
}
/**
* update_cond_flag - Set or reset the TRIGGER_COND bit
* @file: The ftrace_event_file associated with the event
*
* If an event has triggers and any of those triggers has a filter or
* a post_trigger, trigger invocation needs to be deferred until after
* the current event has logged its data, and the event should have
* its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
* cleared.
*/
static void update_cond_flag(struct ftrace_event_file *file)
{
struct event_trigger_data *data;
bool set_cond = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
if (data->filter || data->cmd_ops->post_trigger) {
set_cond = true;
break;
}
}
if (set_cond)
set_bit(FTRACE_EVENT_FL_TRIGGER_COND_BIT, &file->flags);
else
clear_bit(FTRACE_EVENT_FL_TRIGGER_COND_BIT, &file->flags);
}
/**
* register_trigger - Generic event_command @reg implementation
* @glob: The raw string used to register the trigger
* @ops: The trigger ops associated with the trigger
* @data: Trigger-specific data to associate with the trigger
* @file: The ftrace_event_file associated with the event
*
* Common implementation for event trigger registration.
*
* Usually used directly as the @reg method in event command
* implementations.
*
* Return: 0 on success, errno otherwise
*/
static int register_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct ftrace_event_file *file)
{
struct event_trigger_data *test;
int ret = 0;
list_for_each_entry_rcu(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
ret = -EEXIST;
goto out;
}
}
if (data->ops->init) {
ret = data->ops->init(data->ops, data);
if (ret < 0)
goto out;
}
list_add_rcu(&data->list, &file->triggers);
ret++;
if (trace_event_trigger_enable_disable(file, 1) < 0) {
list_del_rcu(&data->list);
ret--;
}
update_cond_flag(file);
out:
return ret;
}
/**
* unregister_trigger - Generic event_command @unreg implementation
* @glob: The raw string used to register the trigger
* @ops: The trigger ops associated with the trigger
* @test: Trigger-specific data used to find the trigger to remove
* @file: The ftrace_event_file associated with the event
*
* Common implementation for event trigger unregistration.
*
* Usually used directly as the @unreg method in event command
* implementations.
*/
static void unregister_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *test,
struct ftrace_event_file *file)
{
struct event_trigger_data *data;
bool unregistered = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
unregistered = true;
list_del_rcu(&data->list);
update_cond_flag(file);
trace_event_trigger_enable_disable(file, 0);
break;
}
}
if (unregistered && data->ops->free)
data->ops->free(data->ops, data);
}
/**
* event_trigger_callback - Generic event_command @func implementation
* @cmd_ops: The command ops, used for trigger registration
* @file: The ftrace_event_file associated with the event
* @glob: The raw string used to register the trigger
* @cmd: The cmd portion of the string used to register the trigger
* @param: The params portion of the string used to register the trigger
*
* Common implementation for event command parsing and trigger
* instantiation.
*
* Usually used directly as the @func method in event command
* implementations.
*
* Return: 0 on success, errno otherwise
*/
static int
event_trigger_callback(struct event_command *cmd_ops,
struct ftrace_event_file *file,
char *glob, char *cmd, char *param)
{
struct event_trigger_data *trigger_data;
struct event_trigger_ops *trigger_ops;
char *trigger = NULL;
char *number;
int ret;
/* separate the trigger from the filter (t:n [if filter]) */
if (param && isdigit(param[0]))
trigger = strsep(&param, " \t");
trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
ret = -ENOMEM;
trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
if (!trigger_data)
goto out;
trigger_data->count = -1;
trigger_data->ops = trigger_ops;
trigger_data->cmd_ops = cmd_ops;
INIT_LIST_HEAD(&trigger_data->list);
if (glob[0] == '!') {
cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
kfree(trigger_data);
ret = 0;
goto out;
}
if (trigger) {
number = strsep(&trigger, ":");
ret = -EINVAL;
if (!strlen(number))
goto out_free;
/*
* We use the callback data field (which is a pointer)
* as our counter.
*/
ret = kstrtoul(number, 0, &trigger_data->count);
if (ret)
goto out_free;
}
if (!param) /* if param is non-empty, it's supposed to be a filter */
goto out_reg;
if (!cmd_ops->set_filter)
goto out_reg;
ret = cmd_ops->set_filter(param, trigger_data, file);
if (ret < 0)
goto out_free;
out_reg:
ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
/*
* The above returns on success the # of functions enabled,
* but if it didn't find any functions it returns zero.
* Consider no functions a failure too.
*/
if (!ret) {
ret = -ENOENT;
goto out_free;
} else if (ret < 0)
goto out_free;
ret = 0;
out:
return ret;
out_free:
if (cmd_ops->set_filter)
cmd_ops->set_filter(NULL, trigger_data, NULL);
kfree(trigger_data);
goto out;
}
/**
* set_trigger_filter - Generic event_command @set_filter implementation
* @filter_str: The filter string for the trigger, NULL to remove filter
* @trigger_data: Trigger-specific data
* @file: The ftrace_event_file associated with the event
*
* Common implementation for event command filter parsing and filter
* instantiation.
*
* Usually used directly as the @set_filter method in event command
* implementations.
*
* Also used to remove a filter (if filter_str = NULL).
*
* Return: 0 on success, errno otherwise
*/
static int set_trigger_filter(char *filter_str,
struct event_trigger_data *trigger_data,
struct ftrace_event_file *file)
{
struct event_trigger_data *data = trigger_data;
struct event_filter *filter = NULL, *tmp;
int ret = -EINVAL;
char *s;
if (!filter_str) /* clear the current filter */
goto assign;
s = strsep(&filter_str, " \t");
if (!strlen(s) || strcmp(s, "if") != 0)
goto out;
if (!filter_str)
goto out;
/* The filter is for the 'trigger' event, not the triggered event */
ret = create_event_filter(file->event_call, filter_str, false, &filter);
if (ret)
goto out;
assign:
tmp = rcu_access_pointer(data->filter);
rcu_assign_pointer(data->filter, filter);
if (tmp) {
/* Make sure the call is done with the filter */
synchronize_sched();
free_event_filter(tmp);
}
kfree(data->filter_str);
data->filter_str = NULL;
if (filter_str) {
data->filter_str = kstrdup(filter_str, GFP_KERNEL);
if (!data->filter_str) {
free_event_filter(rcu_access_pointer(data->filter));
data->filter = NULL;
ret = -ENOMEM;
}
}
out:
return ret;
}
static void
traceon_trigger(struct event_trigger_data *data)
{
if (tracing_is_on())
return;
tracing_on();
}
static void
traceon_count_trigger(struct event_trigger_data *data)
{
if (tracing_is_on())
return;
if (!data->count)
return;
if (data->count != -1)
(data->count)--;
tracing_on();
}
static void
traceoff_trigger(struct event_trigger_data *data)
{
if (!tracing_is_on())
return;
tracing_off();
}
static void
traceoff_count_trigger(struct event_trigger_data *data)
{
if (!tracing_is_on())
return;
if (!data->count)
return;
if (data->count != -1)
(data->count)--;
tracing_off();
}
static int
traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
return event_trigger_print("traceon", m, (void *)data->count,
data->filter_str);
}
static int
traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
return event_trigger_print("traceoff", m, (void *)data->count,
data->filter_str);
}
static struct event_trigger_ops traceon_trigger_ops = {
.func = traceon_trigger,
.print = traceon_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops traceon_count_trigger_ops = {
.func = traceon_count_trigger,
.print = traceon_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops traceoff_trigger_ops = {
.func = traceoff_trigger,
.print = traceoff_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops traceoff_count_trigger_ops = {
.func = traceoff_count_trigger,
.print = traceoff_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops *
onoff_get_trigger_ops(char *cmd, char *param)
{
struct event_trigger_ops *ops;
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = param ? &traceon_count_trigger_ops :
&traceon_trigger_ops;
else
ops = param ? &traceoff_count_trigger_ops :
&traceoff_trigger_ops;
return ops;
}
static struct event_command trigger_traceon_cmd = {
.name = "traceon",
.trigger_type = ETT_TRACE_ONOFF,
.func = event_trigger_callback,
.reg = register_trigger,
.unreg = unregister_trigger,
.get_trigger_ops = onoff_get_trigger_ops,
.set_filter = set_trigger_filter,
};
static struct event_command trigger_traceoff_cmd = {
.name = "traceoff",
.trigger_type = ETT_TRACE_ONOFF,
.func = event_trigger_callback,
.reg = register_trigger,
.unreg = unregister_trigger,
.get_trigger_ops = onoff_get_trigger_ops,
.set_filter = set_trigger_filter,
};
#ifdef CONFIG_TRACER_SNAPSHOT
static void
snapshot_trigger(struct event_trigger_data *data)
{
tracing_snapshot();
}
static void
snapshot_count_trigger(struct event_trigger_data *data)
{
if (!data->count)
return;
if (data->count != -1)
(data->count)--;
snapshot_trigger(data);
}
static int
register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct ftrace_event_file *file)
{
int ret = register_trigger(glob, ops, data, file);
if (ret > 0 && tracing_alloc_snapshot() != 0) {
unregister_trigger(glob, ops, data, file);
ret = 0;
}
return ret;
}
static int
snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
return event_trigger_print("snapshot", m, (void *)data->count,
data->filter_str);
}
static struct event_trigger_ops snapshot_trigger_ops = {
.func = snapshot_trigger,
.print = snapshot_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops snapshot_count_trigger_ops = {
.func = snapshot_count_trigger,
.print = snapshot_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops *
snapshot_get_trigger_ops(char *cmd, char *param)
{
return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
}
static struct event_command trigger_snapshot_cmd = {
.name = "snapshot",
.trigger_type = ETT_SNAPSHOT,
.func = event_trigger_callback,
.reg = register_snapshot_trigger,
.unreg = unregister_trigger,
.get_trigger_ops = snapshot_get_trigger_ops,
.set_filter = set_trigger_filter,
};
static __init int register_trigger_snapshot_cmd(void)
{
int ret;
ret = register_event_command(&trigger_snapshot_cmd);
WARN_ON(ret < 0);
return ret;
}
#else
static __init int register_trigger_snapshot_cmd(void) { return 0; }
#endif /* CONFIG_TRACER_SNAPSHOT */
#ifdef CONFIG_STACKTRACE
/*
* Skip 3:
* stacktrace_trigger()
* event_triggers_post_call()
* ftrace_raw_event_xxx()
*/
#define STACK_SKIP 3
static void
stacktrace_trigger(struct event_trigger_data *data)
{
trace_dump_stack(STACK_SKIP);
}
static void
stacktrace_count_trigger(struct event_trigger_data *data)
{
if (!data->count)
return;
if (data->count != -1)
(data->count)--;
stacktrace_trigger(data);
}
static int
stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
return event_trigger_print("stacktrace", m, (void *)data->count,
data->filter_str);
}
static struct event_trigger_ops stacktrace_trigger_ops = {
.func = stacktrace_trigger,
.print = stacktrace_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops stacktrace_count_trigger_ops = {
.func = stacktrace_count_trigger,
.print = stacktrace_trigger_print,
.init = event_trigger_init,
.free = event_trigger_free,
};
static struct event_trigger_ops *
stacktrace_get_trigger_ops(char *cmd, char *param)
{
return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
}
static struct event_command trigger_stacktrace_cmd = {
.name = "stacktrace",
.trigger_type = ETT_STACKTRACE,
.post_trigger = true,
.func = event_trigger_callback,
.reg = register_trigger,
.unreg = unregister_trigger,
.get_trigger_ops = stacktrace_get_trigger_ops,
.set_filter = set_trigger_filter,
};
static __init int register_trigger_stacktrace_cmd(void)
{
int ret;
ret = register_event_command(&trigger_stacktrace_cmd);
WARN_ON(ret < 0);
return ret;
}
#else
static __init int register_trigger_stacktrace_cmd(void) { return 0; }
#endif /* CONFIG_STACKTRACE */
static __init void unregister_trigger_traceon_traceoff_cmds(void)
{
unregister_event_command(&trigger_traceon_cmd);
unregister_event_command(&trigger_traceoff_cmd);
}
/* Avoid typos */
#define ENABLE_EVENT_STR "enable_event"
#define DISABLE_EVENT_STR "disable_event"
struct enable_trigger_data {
struct ftrace_event_file *file;
bool enable;
};
static void
event_enable_trigger(struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;
if (enable_data->enable)
clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
else
set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
}
static void
event_enable_count_trigger(struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;
if (!data->count)
return;
/* Skip if the event is in a state we want to switch to */
if (enable_data->enable == !(enable_data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
return;
if (data->count != -1)
(data->count)--;
event_enable_trigger(data);
}
static int
event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;
seq_printf(m, "%s:%s:%s",
enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
enable_data->file->event_call->class->system,
ftrace_event_name(enable_data->file->event_call));
if (data->count == -1)
seq_puts(m, ":unlimited");
else
seq_printf(m, ":count=%ld", data->count);
if (data->filter_str)
seq_printf(m, " if %s\n", data->filter_str);
else
seq_puts(m, "\n");
return 0;
}
static void
event_enable_trigger_free(struct event_trigger_ops *ops,
struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;
if (WARN_ON_ONCE(data->ref <= 0))
return;
data->ref--;
if (!data->ref) {
/* Remove the SOFT_MODE flag */
trace_event_enable_disable(enable_data->file, 0, 1);
module_put(enable_data->file->event_call->mod);
trigger_data_free(data);
kfree(enable_data);
}
}
static struct event_trigger_ops event_enable_trigger_ops = {
.func = event_enable_trigger,
.print = event_enable_trigger_print,
.init = event_trigger_init,
.free = event_enable_trigger_free,
};
static struct event_trigger_ops event_enable_count_trigger_ops = {
.func = event_enable_count_trigger,
.print = event_enable_trigger_print,
.init = event_trigger_init,
.free = event_enable_trigger_free,
};
static struct event_trigger_ops event_disable_trigger_ops = {
.func = event_enable_trigger,
.print = event_enable_trigger_print,
.init = event_trigger_init,
.free = event_enable_trigger_free,
};
static struct event_trigger_ops event_disable_count_trigger_ops = {
.func = event_enable_count_trigger,
.print = event_enable_trigger_print,
.init = event_trigger_init,
.free = event_enable_trigger_free,
};
static int
event_enable_trigger_func(struct event_command *cmd_ops,
struct ftrace_event_file *file,
char *glob, char *cmd, char *param)
{
struct ftrace_event_file *event_enable_file;
struct enable_trigger_data *enable_data;
struct event_trigger_data *trigger_data;
struct event_trigger_ops *trigger_ops;
struct trace_array *tr = file->tr;
const char *system;
const char *event;
char *trigger;
char *number;
bool enable;
int ret;
if (!param)
return -EINVAL;
/* separate the trigger from the filter (s:e:n [if filter]) */
trigger = strsep(&param, " \t");
if (!trigger)
return -EINVAL;
system = strsep(&trigger, ":");
if (!trigger)
return -EINVAL;
event = strsep(&trigger, ":");
ret = -EINVAL;
event_enable_file = find_event_file(tr, system, event);
if (!event_enable_file)
goto out;
enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
ret = -ENOMEM;
trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
if (!trigger_data)
goto out;
enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
if (!enable_data) {
kfree(trigger_data);
goto out;
}
trigger_data->count = -1;
trigger_data->ops = trigger_ops;
trigger_data->cmd_ops = cmd_ops;
INIT_LIST_HEAD(&trigger_data->list);
RCU_INIT_POINTER(trigger_data->filter, NULL);
enable_data->enable = enable;
enable_data->file = event_enable_file;
trigger_data->private_data = enable_data;
if (glob[0] == '!') {
cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
kfree(trigger_data);
kfree(enable_data);
ret = 0;
goto out;
}
if (trigger) {
number = strsep(&trigger, ":");
ret = -EINVAL;
if (!strlen(number))
goto out_free;
/*
* We use the callback data field (which is a pointer)
* as our counter.
*/
ret = kstrtoul(number, 0, &trigger_data->count);
if (ret)
goto out_free;
}
if (!param) /* if param is non-empty, it's supposed to be a filter */
goto out_reg;
if (!cmd_ops->set_filter)
goto out_reg;
ret = cmd_ops->set_filter(param, trigger_data, file);
if (ret < 0)
goto out_free;
out_reg:
/* Don't let event modules unload while probe registered */
ret = try_module_get(event_enable_file->event_call->mod);
if (!ret) {
ret = -EBUSY;
goto out_free;
}
ret = trace_event_enable_disable(event_enable_file, 1, 1);
if (ret < 0)
goto out_put;
ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
/*
* The above returns on success the # of functions enabled,
* but if it didn't find any functions it returns zero.
* Consider no functions a failure too.
*/
if (!ret) {
ret = -ENOENT;
goto out_disable;
} else if (ret < 0)
goto out_disable;
/* Just return zero, not the number of enabled functions */
ret = 0;
out:
return ret;
out_disable:
trace_event_enable_disable(event_enable_file, 0, 1);
out_put:
module_put(event_enable_file->event_call->mod);
out_free:
if (cmd_ops->set_filter)
cmd_ops->set_filter(NULL, trigger_data, NULL);
kfree(trigger_data);
kfree(enable_data);
goto out;
}
static int event_enable_register_trigger(char *glob,
struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct ftrace_event_file *file)
{
struct enable_trigger_data *enable_data = data->private_data;
struct enable_trigger_data *test_enable_data;
struct event_trigger_data *test;
int ret = 0;
list_for_each_entry_rcu(test, &file->triggers, list) {
test_enable_data = test->private_data;
if (test_enable_data &&
(test_enable_data->file == enable_data->file)) {
ret = -EEXIST;
goto out;
}
}
if (data->ops->init) {
ret = data->ops->init(data->ops, data);
if (ret < 0)
goto out;
}
list_add_rcu(&data->list, &file->triggers);
ret++;
if (trace_event_trigger_enable_disable(file, 1) < 0) {
list_del_rcu(&data->list);
ret--;
}
update_cond_flag(file);
out:
return ret;
}
static void event_enable_unregister_trigger(char *glob,
struct event_trigger_ops *ops,
struct event_trigger_data *test,
struct ftrace_event_file *file)
{
struct enable_trigger_data *test_enable_data = test->private_data;
struct enable_trigger_data *enable_data;
struct event_trigger_data *data;
bool unregistered = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
enable_data = data->private_data;
if (enable_data &&
(enable_data->file == test_enable_data->file)) {
unregistered = true;
list_del_rcu(&data->list);
update_cond_flag(file);
trace_event_trigger_enable_disable(file, 0);
break;
}
}
if (unregistered && data->ops->free)
data->ops->free(data->ops, data);
}
static struct event_trigger_ops *
event_enable_get_trigger_ops(char *cmd, char *param)
{
struct event_trigger_ops *ops;
bool enable;
enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
if (enable)
ops = param ? &event_enable_count_trigger_ops :
&event_enable_trigger_ops;
else
ops = param ? &event_disable_count_trigger_ops :
&event_disable_trigger_ops;
return ops;
}
static struct event_command trigger_enable_cmd = {
.name = ENABLE_EVENT_STR,
.trigger_type = ETT_EVENT_ENABLE,
.func = event_enable_trigger_func,
.reg = event_enable_register_trigger,
.unreg = event_enable_unregister_trigger,
.get_trigger_ops = event_enable_get_trigger_ops,
.set_filter = set_trigger_filter,
};
static struct event_command trigger_disable_cmd = {
.name = DISABLE_EVENT_STR,
.trigger_type = ETT_EVENT_ENABLE,
.func = event_enable_trigger_func,
.reg = event_enable_register_trigger,
.unreg = event_enable_unregister_trigger,
.get_trigger_ops = event_enable_get_trigger_ops,
.set_filter = set_trigger_filter,
};
static __init void unregister_trigger_enable_disable_cmds(void)
{
unregister_event_command(&trigger_enable_cmd);
unregister_event_command(&trigger_disable_cmd);
}
static __init int register_trigger_enable_disable_cmds(void)
{
int ret;
ret = register_event_command(&trigger_enable_cmd);
if (WARN_ON(ret < 0))
return ret;
ret = register_event_command(&trigger_disable_cmd);
if (WARN_ON(ret < 0))
unregister_trigger_enable_disable_cmds();
return ret;
}
static __init int register_trigger_traceon_traceoff_cmds(void)
{
int ret;
ret = register_event_command(&trigger_traceon_cmd);
if (WARN_ON(ret < 0))
return ret;
ret = register_event_command(&trigger_traceoff_cmd);
if (WARN_ON(ret < 0))
unregister_trigger_traceon_traceoff_cmds();
return ret;
}
__init int register_trigger_cmds(void)
{
register_trigger_traceon_traceoff_cmds();
register_trigger_snapshot_cmd();
register_trigger_stacktrace_cmd();
register_trigger_enable_disable_cmds();
return 0;
}