tracing/function-graph-tracer: display unified style cmdline and pid

Impact: extend function-graph output: let one know which thread called a function

This patch implements a helper function to print the couple cmdline/pid.
Its output is provided during task switching and on each row if the new
"funcgraph-proc" defualt-off option is set through trace_options file.

The output is center aligned and never exceeds 14 characters. The cmdline
is truncated over 7 chars.
But note that if the pid exceeds 6 characters, the column will overflow (but
the situation is abnormal).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 99 insertions, 14 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 894b50bca313..23e19d2dbd06 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -19,6 +19,7 @@
 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
 #define TRACE_GRAPH_PRINT_CPU           0x2
 #define TRACE_GRAPH_PRINT_OVERHEAD      0x4
+#define TRACE_GRAPH_PRINT_PROC          0x8
 
 static struct tracer_opt trace_opts[] = {
         /* Display overruns ? */
@@ -27,11 +28,13 @@ static struct tracer_opt trace_opts[] = {
         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
         /* Display Overhead ? */
         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
+        /* Display proc name/pid */
+        { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
         { } /* Empty entry */
 };
 
 static struct tracer_flags tracer_flags = {
-        /* Don't display overruns by default */
+        /* Don't display overruns and proc by default */
         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD,
         .opts = trace_opts
 };
@@ -104,23 +107,63 @@ print_graph_cpu(struct trace_seq *s, int cpu)
         return TRACE_TYPE_HANDLED;
 }
 
+#define TRACE_GRAPH_PROCINFO_LENGTH     14
+
+static enum print_line_t
+print_graph_proc(struct trace_seq *s, pid_t pid)
+{
+        int i;
+        int ret;
+        int len;
+        char comm[8];
+        int spaces = 0;
+        /* sign + log10(MAX_INT) + '\0' */
+        char pid_str[11];
+
+        strncpy(comm, trace_find_cmdline(pid), 7);
+        comm[7] = '\0';
+        sprintf(pid_str, "%d", pid);
+
+        /* 1 stands for the "-" character */
+        len = strlen(comm) + strlen(pid_str) + 1;
+
+        if (len < TRACE_GRAPH_PROCINFO_LENGTH)
+                spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
+
+        /* First spaces to align center */
+        for (i = 0; i < spaces / 2; i++) {
+                ret = trace_seq_printf(s, " ");
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
+        if (!ret)
+                return TRACE_TYPE_PARTIAL_LINE;
+
+        /* Last spaces to align center */
+        for (i = 0; i < spaces - (spaces / 2); i++) {
+                ret = trace_seq_printf(s, " ");
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+        return TRACE_TYPE_HANDLED;
+}
+
 
 /* If the pid changed since the last trace, output this event */
-static int verif_pid(struct trace_seq *s, pid_t pid, int cpu)
+static enum print_line_t
+verif_pid(struct trace_seq *s, pid_t pid, int cpu)
 {
-        char *comm, *prev_comm;
         pid_t prev_pid;
         int ret;
 
         if (last_pid[cpu] != -1 && last_pid[cpu] == pid)
-                return 1;
+                return TRACE_TYPE_HANDLED;
 
         prev_pid = last_pid[cpu];
         last_pid[cpu] = pid;
 
-        comm = trace_find_cmdline(pid);
-        prev_comm = trace_find_cmdline(prev_pid);
-
 /*
  * Context-switch trace line:
 
@@ -130,11 +173,31 @@ static int verif_pid(struct trace_seq *s, pid_t pid, int cpu)
 
  */
         ret = trace_seq_printf(s,
-                " ------------------------------------------\n");
-        ret += trace_seq_printf(s, " | %d)  %s-%d  =>  %s-%d\n",
-                                  cpu, prev_comm, prev_pid, comm, pid);
-        ret += trace_seq_printf(s,
-                " ------------------------------------------\n\n");
+                "\n ------------------------------------------\n |");
+        if (!ret)
+                TRACE_TYPE_PARTIAL_LINE;
+
+        ret = print_graph_cpu(s, cpu);
+        if (ret == TRACE_TYPE_PARTIAL_LINE)
+                TRACE_TYPE_PARTIAL_LINE;
+
+        ret = print_graph_proc(s, prev_pid);
+        if (ret == TRACE_TYPE_PARTIAL_LINE)
+                TRACE_TYPE_PARTIAL_LINE;
+
+        ret = trace_seq_printf(s, " => ");
+        if (!ret)
+                TRACE_TYPE_PARTIAL_LINE;
+
+        ret = print_graph_proc(s, pid);
+        if (ret == TRACE_TYPE_PARTIAL_LINE)
+                TRACE_TYPE_PARTIAL_LINE;
+
+        ret = trace_seq_printf(s,
+                "\n ------------------------------------------\n\n");
+        if (!ret)
+                TRACE_TYPE_PARTIAL_LINE;
+
         return ret;
 }
 
@@ -288,12 +351,23 @@ print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
         struct trace_entry *ent = iter->ent;
 
         /* Pid */
-        if (!verif_pid(s, ent->pid, cpu))
+        if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
                 return TRACE_TYPE_PARTIAL_LINE;
 
         /* Cpu */
         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
                 ret = print_graph_cpu(s, cpu);
+                if (ret == TRACE_TYPE_PARTIAL_LINE)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        /* Proc */
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
+                ret = print_graph_proc(s, ent->pid);
+                if (ret == TRACE_TYPE_PARTIAL_LINE)
+                        return TRACE_TYPE_PARTIAL_LINE;
+
+                ret = trace_seq_printf(s, " | ");
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
@@ -318,12 +392,23 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
                 duration = 9999999ULL;
 
         /* Pid */
-        if (!verif_pid(s, ent->pid, cpu))
+        if (verif_pid(s, ent->pid, cpu) == TRACE_TYPE_PARTIAL_LINE)
                 return TRACE_TYPE_PARTIAL_LINE;
 
         /* Cpu */
         if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
                 ret = print_graph_cpu(s, cpu);
+                if (ret == TRACE_TYPE_PARTIAL_LINE)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
+
+        /* Proc */
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
+                ret = print_graph_proc(s, ent->pid);
+                if (ret == TRACE_TYPE_PARTIAL_LINE)
+                        return TRACE_TYPE_PARTIAL_LINE;
+
+                ret = trace_seq_printf(s, " | ");
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }