tracing/syscalls: Fix the output of syscalls with no arguments

Before:

  # echo 1 > events/syscalls/sys_enter_sync/enable
  # cat events/syscalls/sys_enter_sync/format
  ...
        field:int nr;   offset:12;      size:4;

  print fmt: "# sync
  # cat trace
  ...
            sync-8950  [000]  2366.087670: sys_sync(

After:

  # echo 1 > events/syscalls/sys_enter_sync/enable
  # cat events/syscalls/sys_enter_sync/format
  ...
        field:int nr;   offset:12;      size:4;

  print fmt: ""
  # sync
  # cat trace
            sync-2134  [001]   136.780735: sys_sync()

Reported-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <4A8D05AF.20103@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 28e4dae..46c1b97 100644 (file)
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -46,15 +46,22 @@ print_syscall_enter(struct trace_iterator *iter, int flags)
                                return TRACE_TYPE_PARTIAL_LINE;
                }
                /* parameter values */
-               ret = trace_seq_printf(s, "%s: %lx%s ", entry->args[i],
+               ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
                                       trace->args[i],
-                                      i == entry->nb_args - 1 ? ")" : ",");
+                                      i == entry->nb_args - 1 ? "" : ", ");
                if (!ret)
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
+       ret = trace_seq_putc(s, ')');
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
 end:
-       trace_seq_printf(s, "\n");
+       ret =  trace_seq_putc(s, '\n');
+       if (!ret)
+               return TRACE_TYPE_PARTIAL_LINE;
+
        return TRACE_TYPE_HANDLED;
 }
 
@@ -129,24 +136,24 @@ int syscall_enter_format(struct ftrace_event_call *call, struct trace_seq *s)
                offset += sizeof(unsigned long);
        }
 
-       trace_seq_printf(s, "\nprint fmt: \"");
+       trace_seq_puts(s, "\nprint fmt: \"");
        for (i = 0; i < entry->nb_args; i++) {
                ret = trace_seq_printf(s, "%s: 0x%%0%zulx%s", entry->args[i],
                                        sizeof(unsigned long),
-                                       i == entry->nb_args - 1 ? "\", " : ", ");
+                                       i == entry->nb_args - 1 ? "" : ", ");
                if (!ret)
                        return 0;
        }
+       trace_seq_putc(s, '"');
 
        for (i = 0; i < entry->nb_args; i++) {
-               ret = trace_seq_printf(s, "((unsigned long)(REC->%s))%s",
-                                       entry->args[i],
-                                       i == entry->nb_args - 1 ? "\n" : ", ");
+               ret = trace_seq_printf(s, ", ((unsigned long)(REC->%s))",
+                                      entry->args[i]);
                if (!ret)
                        return 0;
        }
 
-       return ret;
+       return trace_seq_putc(s, '\n');
 }
 
 int syscall_exit_format(struct ftrace_event_call *call, struct trace_seq *s)