core: Inject subtest message into dmesg

One of the side-effects we test for are kernel oops and knowing the
guilty subtest can help speed up debugging. We can write to /dev/kmsg to
inject messages into dmesg, so let's do so before the start of every
test.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/lib/igt_core.c b/lib/igt_core.c
index b0800e8..9196428 100644 (file)
--- a/lib/igt_core.c
+++ b/lib/igt_core.c
@@ -269,8 +269,9 @@ static void print_version(void)
                uts.sysname, uts.release, uts.machine);
 }
 
-static void print_usage(const char *command_str, const char *help_str,
-                       bool output_on_stderr)
+static const char *command_str;
+
+static void print_usage(const char *help_str, bool output_on_stderr)
 {
        FILE *f = output_on_stderr ? stderr : stdout;
 
@@ -306,7 +307,6 @@ static int common_init(int argc, char **argv,
                {"debug", 0, 0, 'd'},
                {"help", 0, 0, 'h'},
        };
-       const char *command_str;
        char *short_opts;
        struct option *combined_opts;
        int extra_opt_count;
@@ -364,11 +364,11 @@ static int common_init(int argc, char **argv,
                                run_single_subtest = strdup(optarg);
                        break;
                case 'h':
-                       print_usage(command_str, help_str, false);
+                       print_usage(help_str, false);
                        ret = -1;
                        goto out;
                case '?':
-                       print_usage(command_str, help_str, true);
+                       print_usage(help_str, true);
                        ret = -2;
                        goto out;
                default:
@@ -498,6 +498,24 @@ void igt_simple_init_parse_opts(int argc, char **argv,
                    extra_opt_handler);
 }
 
+__attribute__((format(printf, 1, 2)))
+static void kmsg(const char *format, ...)
+#define KERN_INFO "<5>"
+{
+       va_list ap;
+       FILE *file;
+
+       file = fopen("/dev/kmsg", "w");
+       if (file == NULL)
+               return;
+
+       va_start(ap, format);
+       vfprintf(file, format, ap);
+       va_end(ap);
+
+       fclose(file);
+}
+
 /*
  * Note: Testcases which use these helpers MUST NOT output anything to stdout
  * outside of places protected by igt_run_subtest checks - the piglit
@@ -529,6 +547,8 @@ bool __igt_run_subtest(const char *subtest_name)
                return false;
        }
 
+       kmsg(KERN_INFO "%s: starting subtest %s\n", command_str, subtest_name);
+
        return (in_subtest = subtest_name);
 }