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tracing: Add support for recording tgid of tasks 

Inorder to support recording of tgid, the following changes are made:

* Introduce a new API (tracing_record_taskinfo) to additionally record the tgid
  along with the task's comm at the same time. This has has the benefit of not
  setting trace_cmdline_save before all the information for a task is saved.
* Add a new API tracing_record_taskinfo_sched_switch to record task information
  for 2 tasks at a time (previous and next) and use it from sched_switch probe.
* Preserve the old API (tracing_record_cmdline) and create it as a wrapper
  around the new one so that existing callers aren't affected.
* Reuse the existing sched_switch and sched_wakeup probes to record tgid
  information and add a new option 'record-tgid' to enable recording of tgid

When record-tgid option isn't enabled to being with, we take care to make sure
that there's isn't memory or runtime overhead.

Link: http://lkml.kernel.org/r/20170627020155.5139-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Tested-by: Michael Sartain <mikesart@gmail.com>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Joel Fernandes 2017-06-26 19:01:55 -07:00 committed by Steven Rostedt (VMware)
parent 83dd14933e
commit d914ba37d7
5 changed files with 213 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/trace_events.h
View File

@ -151,7 +151,15 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_buffer,
int type, unsigned long len,
unsigned long flags, int pc);
void tracing_record_cmdline(struct task_struct *tsk);
#define TRACE_RECORD_CMDLINE BIT(0)
#define TRACE_RECORD_TGID BIT(1)
void tracing_record_taskinfo(struct task_struct *task, int flags);
void tracing_record_taskinfo_sched_switch(struct task_struct *prev,
struct task_struct *next, int flags);
void tracing_record_cmdline(struct task_struct *task);
void tracing_record_tgid(struct task_struct *task);
int trace_output_call(struct trace_iterator *iter, char *name, char *fmt, ...);
@ -290,6 +298,7 @@ struct trace_subsystem_dir;
enum {
EVENT_FILE_FL_ENABLED_BIT,
EVENT_FILE_FL_RECORDED_CMD_BIT,
EVENT_FILE_FL_RECORDED_TGID_BIT,
EVENT_FILE_FL_FILTERED_BIT,
EVENT_FILE_FL_NO_SET_FILTER_BIT,
EVENT_FILE_FL_SOFT_MODE_BIT,
@ -303,6 +312,7 @@ enum {
* Event file flags:
* ENABLED - The event is enabled
* RECORDED_CMD - The comms should be recorded at sched_switch
* RECORDED_TGID - The tgids should be recorded at sched_switch
* FILTERED - The event has a filter attached
* NO_SET_FILTER - Set when filter has error and is to be ignored
* SOFT_MODE - The event is enabled/disabled by SOFT_DISABLED
@ -315,6 +325,7 @@ enum {
enum {
EVENT_FILE_FL_ENABLED = (1 << EVENT_FILE_FL_ENABLED_BIT),
EVENT_FILE_FL_RECORDED_CMD = (1 << EVENT_FILE_FL_RECORDED_CMD_BIT),
EVENT_FILE_FL_RECORDED_TGID = (1 << EVENT_FILE_FL_RECORDED_TGID_BIT),
EVENT_FILE_FL_FILTERED = (1 << EVENT_FILE_FL_FILTERED_BIT),
EVENT_FILE_FL_NO_SET_FILTER = (1 << EVENT_FILE_FL_NO_SET_FILTER_BIT),
EVENT_FILE_FL_SOFT_MODE = (1 << EVENT_FILE_FL_SOFT_MODE_BIT),

105
kernel/trace/trace.c
View File

@ -87,7 +87,7 @@ dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
* tracing is active, only save the comm when a trace event
* occurred.
*/
static DEFINE_PER_CPU(bool, trace_cmdline_save);
static DEFINE_PER_CPU(bool, trace_taskinfo_save);
/*
* Kill all tracing for good (never come back).
@ -790,7 +790,7 @@ EXPORT_SYMBOL_GPL(tracing_on);
static __always_inline void
__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
{
__this_cpu_write(trace_cmdline_save, true);
__this_cpu_write(trace_taskinfo_save, true);
/* If this is the temp buffer, we need to commit fully */
if (this_cpu_read(trace_buffered_event) == event) {
@ -1709,6 +1709,8 @@ void tracing_reset_all_online_cpus(void)
}
}
static int *tgid_map;
#define SAVED_CMDLINES_DEFAULT 128
#define NO_CMDLINE_MAP UINT_MAX
static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
@ -1722,7 +1724,7 @@ struct saved_cmdlines_buffer {
static struct saved_cmdlines_buffer *savedcmd;
/* temporary disable recording */
static atomic_t trace_record_cmdline_disabled __read_mostly;
static atomic_t trace_record_taskinfo_disabled __read_mostly;
static inline char *get_saved_cmdlines(int idx)
{
@ -1990,16 +1992,87 @@ void trace_find_cmdline(int pid, char comm[])
preempt_enable();
}
void tracing_record_cmdline(struct task_struct *tsk)
int trace_find_tgid(int pid)
{
if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
if (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT))
return 0;
return tgid_map[pid];
}
static int trace_save_tgid(struct task_struct *tsk)
{
if (unlikely(!tgid_map || !tsk->pid || tsk->pid > PID_MAX_DEFAULT))
return 0;
tgid_map[tsk->pid] = tsk->tgid;
return 1;
}
static bool tracing_record_taskinfo_skip(int flags)
{
if (unlikely(!(flags & (TRACE_RECORD_CMDLINE | TRACE_RECORD_TGID))))
return true;
if (atomic_read(&trace_record_taskinfo_disabled) || !tracing_is_on())
return true;
if (!__this_cpu_read(trace_taskinfo_save))
return true;
return false;
}
/**
* tracing_record_taskinfo - record the task info of a task
*
* @task - task to record
* @flags - TRACE_RECORD_CMDLINE for recording comm
* - TRACE_RECORD_TGID for recording tgid
*/
void tracing_record_taskinfo(struct task_struct *task, int flags)
{
if (tracing_record_taskinfo_skip(flags))
return;
if ((flags & TRACE_RECORD_CMDLINE) && !trace_save_cmdline(task))
return;
if ((flags & TRACE_RECORD_TGID) && !trace_save_tgid(task))
return;
if (!__this_cpu_read(trace_cmdline_save))
__this_cpu_write(trace_taskinfo_save, false);
}
/**
* tracing_record_taskinfo_sched_switch - record task info for sched_switch
*
* @prev - previous task during sched_switch
* @next - next task during sched_switch
* @flags - TRACE_RECORD_CMDLINE for recording comm
* TRACE_RECORD_TGID for recording tgid
*/
void tracing_record_taskinfo_sched_switch(struct task_struct *prev,
struct task_struct *next, int flags)
{
if (tracing_record_taskinfo_skip(flags))
return;
if (trace_save_cmdline(tsk))
__this_cpu_write(trace_cmdline_save, false);
if ((flags & TRACE_RECORD_CMDLINE) &&
(!trace_save_cmdline(prev) || !trace_save_cmdline(next)))
return;
if ((flags & TRACE_RECORD_TGID) &&
(!trace_save_tgid(prev) || !trace_save_tgid(next)))
return;
__this_cpu_write(trace_taskinfo_save, false);
}
/* Helpers to record a specific task information */
void tracing_record_cmdline(struct task_struct *task)
{
tracing_record_taskinfo(task, TRACE_RECORD_CMDLINE);
}
void tracing_record_tgid(struct task_struct *task)
{
tracing_record_taskinfo(task, TRACE_RECORD_TGID);
}
/*
@ -3144,7 +3217,7 @@ static void *s_start(struct seq_file *m, loff_t *pos)
#endif
if (!iter->snapshot)
atomic_inc(&trace_record_cmdline_disabled);
atomic_inc(&trace_record_taskinfo_disabled);
if (*pos != iter->pos) {
iter->ent = NULL;
@ -3189,7 +3262,7 @@ static void s_stop(struct seq_file *m, void *p)
#endif
if (!iter->snapshot)
atomic_dec(&trace_record_cmdline_disabled);
atomic_dec(&trace_record_taskinfo_disabled);
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
@ -4236,6 +4309,18 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
if (mask == TRACE_ITER_RECORD_CMD)
trace_event_enable_cmd_record(enabled);
if (mask == TRACE_ITER_RECORD_TGID) {
if (!tgid_map)
tgid_map = kzalloc((PID_MAX_DEFAULT + 1) * sizeof(*tgid_map),
GFP_KERNEL);
if (!tgid_map) {
tr->trace_flags &= ~TRACE_ITER_RECORD_TGID;
return -ENOMEM;
}
trace_event_enable_tgid_record(enabled);
}
if (mask == TRACE_ITER_EVENT_FORK)
trace_event_follow_fork(tr, enabled);

7
kernel/trace/trace.h
View File

@ -640,6 +640,9 @@ void set_graph_array(struct trace_array *tr);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
void tracing_start_tgid_record(void);
void tracing_stop_tgid_record(void);
int register_tracer(struct tracer *type);
int is_tracing_stopped(void);
@ -700,6 +703,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
extern u64 ftrace_now(int cpu);
extern void trace_find_cmdline(int pid, char comm[]);
extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);
#ifdef CONFIG_DYNAMIC_FTRACE
@ -1124,6 +1128,7 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
C(CONTEXT_INFO, "context-info"), /* Print pid/cpu/time */ \
C(LATENCY_FMT, "latency-format"), \
C(RECORD_CMD, "record-cmd"), \
C(RECORD_TGID, "record-tgid"), \
C(OVERWRITE, "overwrite"), \
C(STOP_ON_FREE, "disable_on_free"), \
C(IRQ_INFO, "irq-info"), \
@ -1440,6 +1445,8 @@ struct ftrace_event_field *
trace_find_event_field(struct trace_event_call *call, char *name);
extern void trace_event_enable_cmd_record(bool enable);
extern void trace_event_enable_tgid_record(bool enable);
extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
extern int event_trace_del_tracer(struct trace_array *tr);

42
kernel/trace/trace_events.c
View File

@ -343,6 +343,28 @@ void trace_event_enable_cmd_record(bool enable)
mutex_unlock(&event_mutex);
}
void trace_event_enable_tgid_record(bool enable)
{
struct trace_event_file *file;
struct trace_array *tr;
mutex_lock(&event_mutex);
do_for_each_event_file(tr, file) {
if (!(file->flags & EVENT_FILE_FL_ENABLED))
continue;
if (enable) {
tracing_start_tgid_record();
set_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
} else {
tracing_stop_tgid_record();
clear_bit(EVENT_FILE_FL_RECORDED_TGID_BIT,
&file->flags);
}
} while_for_each_event_file();
mutex_unlock(&event_mutex);
}
static int __ftrace_event_enable_disable(struct trace_event_file *file,
int enable, int soft_disable)
{
@ -381,6 +403,12 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
tracing_stop_cmdline_record();
clear_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
}
if (file->flags & EVENT_FILE_FL_RECORDED_TGID) {
tracing_stop_tgid_record();
clear_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
}
call->class->reg(call, TRACE_REG_UNREGISTER, file);
}
/* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
@ -407,18 +435,30 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
}
if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
bool cmd = false, tgid = false;
/* Keep the event disabled, when going to SOFT_MODE. */
if (soft_disable)
set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
if (tr->trace_flags & TRACE_ITER_RECORD_CMD) {
cmd = true;
tracing_start_cmdline_record();
set_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
}
if (tr->trace_flags & TRACE_ITER_RECORD_TGID) {
tgid = true;
tracing_start_tgid_record();
set_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
}
ret = call->class->reg(call, TRACE_REG_REGISTER, file);
if (ret) {
tracing_stop_cmdline_record();
if (cmd)
tracing_stop_cmdline_record();
if (tgid)
tracing_stop_tgid_record();
pr_info("event trace: Could not enable event "
"%s\n", trace_event_name(call));
break;

72
kernel/trace/trace_sched_switch.c
View File

@ -12,27 +12,38 @@
#include "trace.h"
static int sched_ref;
#define RECORD_CMDLINE 1
#define RECORD_TGID 2
static int sched_cmdline_ref;
static int sched_tgid_ref;
static DEFINE_MUTEX(sched_register_mutex);
static void
probe_sched_switch(void *ignore, bool preempt,
struct task_struct *prev, struct task_struct *next)
{
if (unlikely(!sched_ref))
return;
int flags;
tracing_record_cmdline(prev);
tracing_record_cmdline(next);
flags = (RECORD_TGID * !!sched_tgid_ref) +
(RECORD_CMDLINE * !!sched_cmdline_ref);
if (!flags)
return;
tracing_record_taskinfo_sched_switch(prev, next, flags);
}
static void
probe_sched_wakeup(void *ignore, struct task_struct *wakee)
{
if (unlikely(!sched_ref))
return;
int flags;
tracing_record_cmdline(current);
flags = (RECORD_TGID * !!sched_tgid_ref) +
(RECORD_CMDLINE * !!sched_cmdline_ref);
if (!flags)
return;
tracing_record_taskinfo(current, flags);
}
static int tracing_sched_register(void)
@ -75,28 +86,61 @@ static void tracing_sched_unregister(void)
unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
}
static void tracing_start_sched_switch(void)
static void tracing_start_sched_switch(int ops)
{
bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
mutex_lock(&sched_register_mutex);
if (!(sched_ref++))
switch (ops) {
case RECORD_CMDLINE:
sched_cmdline_ref++;
break;
case RECORD_TGID:
sched_tgid_ref++;
break;
}
if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
tracing_sched_register();
mutex_unlock(&sched_register_mutex);
}
static void tracing_stop_sched_switch(void)
static void tracing_stop_sched_switch(int ops)
{
mutex_lock(&sched_register_mutex);
if (!(--sched_ref))
switch (ops) {
case RECORD_CMDLINE:
sched_cmdline_ref--;
break;
case RECORD_TGID:
sched_tgid_ref--;
break;
}
if (!sched_cmdline_ref && !sched_tgid_ref)
tracing_sched_unregister();
mutex_unlock(&sched_register_mutex);
}
void tracing_start_cmdline_record(void)
{
tracing_start_sched_switch();
tracing_start_sched_switch(RECORD_CMDLINE);
}
void tracing_stop_cmdline_record(void)
{
tracing_stop_sched_switch();
tracing_stop_sched_switch(RECORD_CMDLINE);
}
void tracing_start_tgid_record(void)
{
tracing_start_sched_switch(RECORD_TGID);
}
void tracing_stop_tgid_record(void)
{
tracing_stop_sched_switch(RECORD_TGID);
}