trace: Add an option to show tgids in trace output

The tgids are tracked along side the saved_cmdlines tracking, and can be
included in trace output by enabling the 'print-tgid' trace option. This is
useful when doing post-processing of the trace data, as it allows events to be
grouped by tgid.

Change-Id: I52ed04c3a8ca7fddbb868b792ce5d21ceb76250e
Signed-off-by: Jamie Gennis <jgennis@google.com>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e71a8be4a6ee9decd1429eb13159885f8c567469..28f007ac99381862a8fe4b75dc884189774e16ac 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -636,6 +636,7 @@ static const char *trace_options[] = {
        "irq-info",
        "markers",
        "function-trace",
+       "print-tgid",
        NULL
 };
 
@@ -1151,6 +1152,7 @@ void tracing_reset_all_online_cpus(void)
 static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
 static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
 static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
+static unsigned saved_tgids[SAVED_CMDLINES];
 static int cmdline_idx;
 static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 
@@ -1354,6 +1356,7 @@ static void trace_save_cmdline(struct task_struct *tsk)
        }
 
        memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
+       saved_tgids[idx] = tsk->tgid;
 
        arch_spin_unlock(&trace_cmdline_lock);
 }
@@ -1389,6 +1392,25 @@ void trace_find_cmdline(int pid, char comm[])
        preempt_enable();
 }
 
+int trace_find_tgid(int pid)
+{
+       unsigned map;
+       int tgid;
+
+       preempt_disable();
+       arch_spin_lock(&trace_cmdline_lock);
+       map = map_pid_to_cmdline[pid];
+       if (map != NO_CMDLINE_MAP)
+               tgid = saved_tgids[map];
+       else
+               tgid = -1;
+
+       arch_spin_unlock(&trace_cmdline_lock);
+       preempt_enable();
+
+       return tgid;
+}
+
 void tracing_record_cmdline(struct task_struct *tsk)
 {
        if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
@@ -2345,6 +2367,13 @@ static void print_func_help_header(struct trace_buffer *buf, struct seq_file *m)
        seq_puts(m, "#              | |       |          |         |\n");
 }
 
+static void print_func_help_header_tgid(struct trace_buffer *buf, struct seq_file *m)
+{
+       print_event_info(buf, m);
+       seq_puts(m, "#           TASK-PID    TGID   CPU#      TIMESTAMP  FUNCTION\n");
+       seq_puts(m, "#              | |        |      |          |         |\n");
+}
+
 static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file *m)
 {
        print_event_info(buf, m);
@@ -2357,6 +2386,18 @@ static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file
        seq_puts(m, "#              | |       |   ||||       |         |\n");
 }
 
+static void print_func_help_header_irq_tgid(struct trace_buffer *buf, struct seq_file *m)
+{
+       print_event_info(buf, m);
+       seq_puts(m, "#                                      _-----=> irqs-off\n");
+       seq_puts(m, "#                                     / _----=> need-resched\n");
+       seq_puts(m, "#                                    | / _---=> hardirq/softirq\n");
+       seq_puts(m, "#                                    || / _--=> preempt-depth\n");
+       seq_puts(m, "#                                    ||| /     delay\n");
+       seq_puts(m, "#           TASK-PID    TGID   CPU#  ||||    TIMESTAMP  FUNCTION\n");
+       seq_puts(m, "#              | |        |      |   ||||       |         |\n");
+}
+
 void
 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 {
@@ -2657,9 +2698,15 @@ void trace_default_header(struct seq_file *m)
        } else {
                if (!(trace_flags & TRACE_ITER_VERBOSE)) {
                        if (trace_flags & TRACE_ITER_IRQ_INFO)
-                               print_func_help_header_irq(iter->trace_buffer, m);
+                               if (trace_flags & TRACE_ITER_TGID)
+                                       print_func_help_header_irq_tgid(iter->trace_buffer, m);
+                               else
+                                       print_func_help_header_irq(iter->trace_buffer, m);
                        else
-                               print_func_help_header(iter->trace_buffer, m);
+                               if (trace_flags & TRACE_ITER_TGID)
+                                       print_func_help_header_tgid(iter->trace_buffer, m);
+                               else
+                                       print_func_help_header(iter->trace_buffer, m);
                }
        }
 }
@@ -3449,9 +3496,53 @@ tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
 }
 
 static const struct file_operations tracing_saved_cmdlines_fops = {
-    .open       = tracing_open_generic,
-    .read       = tracing_saved_cmdlines_read,
-    .llseek    = generic_file_llseek,
+       .open   = tracing_open_generic,
+       .read   = tracing_saved_cmdlines_read,
+       .llseek = generic_file_llseek,
+};
+
+static ssize_t
+tracing_saved_tgids_read(struct file *file, char __user *ubuf,
+                               size_t cnt, loff_t *ppos)
+{
+       char *file_buf;
+       char *buf;
+       int len = 0;
+       int pid;
+       int i;
+
+       file_buf = kmalloc(SAVED_CMDLINES*(16+1+16), GFP_KERNEL);
+       if (!file_buf)
+               return -ENOMEM;
+
+       buf = file_buf;
+
+       for (i = 0; i < SAVED_CMDLINES; i++) {
+               int tgid;
+               int r;
+
+               pid = map_cmdline_to_pid[i];
+               if (pid == -1 || pid == NO_CMDLINE_MAP)
+                       continue;
+
+               tgid = trace_find_tgid(pid);
+               r = sprintf(buf, "%d %d\n", pid, tgid);
+               buf += r;
+               len += r;
+       }
+
+       len = simple_read_from_buffer(ubuf, cnt, ppos,
+                                     file_buf, len);
+
+       kfree(file_buf);
+
+       return len;
+}
+
+static const struct file_operations tracing_saved_tgids_fops = {
+       .open   = tracing_open_generic,
+       .read   = tracing_saved_tgids_read,
+       .llseek = generic_file_llseek,
 };
 
 static ssize_t
@@ -5939,6 +6030,9 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
        trace_create_file("trace_marker", 0220, d_tracer,
                          tr, &tracing_mark_fops);
 
+       trace_create_file("saved_tgids", 0444, d_tracer,
+                         tr, &tracing_saved_tgids_fops);
+
        trace_create_file("trace_clock", 0644, d_tracer, tr,
                          &trace_clock_fops);
 

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 20572ed88c5c3b791bef107aab7fbc1f3b0b44d1..6c42f187592c644ada35d15c969457b948e170a1 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -648,6 +648,7 @@ static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
 extern cycle_t ftrace_now(int cpu);
 
 extern void trace_find_cmdline(int pid, char comm[]);
+extern int trace_find_tgid(int pid);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 extern unsigned long ftrace_update_tot_cnt;
@@ -861,6 +862,7 @@ enum trace_iterator_flags {
        TRACE_ITER_IRQ_INFO             = 0x800000,
        TRACE_ITER_MARKERS              = 0x1000000,
        TRACE_ITER_FUNCTION             = 0x2000000,
+       TRACE_ITER_TGID                 = 0x4000000,
 };
 
 /*

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index bb922d9ee51ba7b51171db284f6cd20576b012b2..31994d2845ea2aa0ec5a67295167662376718676 100644 (file)
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -702,11 +702,25 @@ int trace_print_context(struct trace_iterator *iter)
        unsigned long secs, usec_rem;
        char comm[TASK_COMM_LEN];
        int ret;
+       int tgid;
 
        trace_find_cmdline(entry->pid, comm);
 
-       ret = trace_seq_printf(s, "%16s-%-5d [%03d] ",
-                              comm, entry->pid, iter->cpu);
+       ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
+       if (!ret)
+               return 0;
+
+       if (trace_flags & TRACE_ITER_TGID) {
+               tgid = trace_find_tgid(entry->pid);
+               if (tgid < 0)
+                       ret = trace_seq_puts(s, "(-----) ");
+               else
+                       ret = trace_seq_printf(s, "(%5d) ", tgid);
+               if (!ret)
+                       return 0;
+       }
+
+       ret = trace_seq_printf(s, "[%03d] ", iter->cpu);
        if (!ret)
                return 0;