[PATCH] Add support for killing running trace

Sometimes if the program dies, it's really annoying to not be able to
terminate a running trace. Add option -k to manually kill such a trace.

diff --git a/blktrace.c b/blktrace.c
index 1084699556a2a1e78b4f106441256deadfb6b868..43837f433853d0c40e8d88846100285762ad3a2f 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -65,7 +65,7 @@ struct mask_map mask_maps[] = {
        DECLARE_MASK_MAP(PC),
 };
 
-#define S_OPTS "d:a:A:r:o:"
+#define S_OPTS "d:a:A:r:o:k"
 static struct option l_opts[] = {
        {
                .name = "dev",
@@ -97,6 +97,12 @@ static struct option l_opts[] = {
                .flag = NULL,
                .val = 'o'
        },
+       {
+               .name = "kill",
+               .has_arg = 0,
+               .flag = NULL,
+               .val = 'k'
+       },
        {
                .name = NULL,
                .has_arg = 0,
@@ -130,6 +136,7 @@ static char *dev;
 static char *output_name;
 static int act_mask = ~0U;
 static int trace_started;
+static int kill_running_trace;
 
 static pthread_mutex_t stdout_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -148,12 +155,6 @@ static int start_trace(char *dev)
 {
        struct blk_user_trace_setup buts;
 
-       devfd = open(dev, O_RDONLY);
-       if (devfd < 0) {
-               perror(dev);
-               return 1;
-       }
-
        memset(&buts, sizeof(buts), 0);
        buts.buf_size = BUF_SIZE;
        buts.buf_nr = BUF_NR;
@@ -171,11 +172,10 @@ static int start_trace(char *dev)
 
 static void stop_trace(void)
 {
-       if (trace_started) {
+       if (trace_started || kill_running_trace) {
                if (ioctl(devfd, BLKSTOPTRACE) < 0)
                        perror("BLKSTOPTRACE");
 
-               close(devfd);
                trace_started = 0;
        }
 }
@@ -418,6 +418,9 @@ int main(int argc, char *argv[])
                case 'o':
                        output_name = strdup(optarg);
                        break;
+               case 'k':
+                       kill_running_trace = 1;
+                       break;
 
                default:
                        fprintf(stderr,"Usage: %s -d <dev> "
@@ -444,10 +447,21 @@ int main(int argc, char *argv[])
                return 2;
        }
 
+       devfd = open(dev, O_RDONLY);
+       if (devfd < 0) {
+               perror(dev);
+               return 3;
+       }
+
+       if (kill_running_trace) {
+               stop_trace();
+               exit(0);
+       }
+
        if (start_trace(dev)) {
                close(devfd);
                fprintf(stderr, "Failed to start trace on %s\n", dev);
-               return 3;
+               return 4;
        }
 
        setlocale(LC_NUMERIC, "en_US");
@@ -459,7 +473,7 @@ int main(int argc, char *argv[])
        if (!i) {
                fprintf(stderr, "Failed to start worker threads\n");
                stop_trace();
-               return 4;
+               return 5;
        }
 
        signal(SIGINT, handle_sigint);
@@ -474,6 +488,7 @@ int main(int argc, char *argv[])
        stop_threads();
        stop_trace();
        show_stats();
+       close(devfd);
 
        return 0;
 }