[for-next][PATCH 10/12] tracing: Add support for recording tgid of tasks
From: Steven Rostedt
Date: Thu Jun 29 2017 - 20:41:32 EST
From: Joel Fernandes <joelaf@xxxxxxxxxx>
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@xxxxxxxxxx
Cc: kernel-team@xxxxxxxxxxx
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Michael Sartain <mikesart@xxxxxxxxx>
Signed-off-by: Joel Fernandes <joelaf@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
include/linux/trace_events.h | 13 ++++-
kernel/trace/trace.c | 105 ++++++++++++++++++++++++++++++++++----
kernel/trace/trace.h | 7 +++
kernel/trace/trace_events.c | 42 ++++++++++++++-
kernel/trace/trace_sched_switch.c | 72 +++++++++++++++++++++-----
5 files changed, 213 insertions(+), 26 deletions(-)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index a556805eff8a..f73cedfa2e0b 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -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),
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 14318ce92b13..ab9db750dd29 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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 (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT))
+ return 0;
+
+ return tgid_map[pid];
+}
+
+static int trace_save_tgid(struct task_struct *tsk)
{
- if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
+ 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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 13823951e42b..6ade1c55cc3a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 83dfd0dbbbfe..36132f9280e6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -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;
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 4c896a0101bd..b341c02730be 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -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;
+
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
- tracing_record_cmdline(prev);
- tracing_record_cmdline(next);
+ 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;
+
+ flags = (RECORD_TGID * !!sched_tgid_ref) +
+ (RECORD_CMDLINE * !!sched_cmdline_ref);
- tracing_record_cmdline(current);
+ 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);
}
--
2.10.2