blktrace: don't stop tracer if not setup trace successfully

if we run blktrace on same device twice, the second time will failed
to ioctl(BLKTRACESETUP), then it will call __stop_tracer, which lead
the first blktrace failed to access debugfs entries. So this patch add
a check to handle this case, to avoid stop tracer uncondionally.

Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/blktrace.c b/blktrace.c
index e048f687c4feb7822718b8f24edea3e7b0295c9b..d0d271f9add5106b4481321058787f1ba1aa82a4 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -112,6 +112,7 @@ struct devpath {
        struct cl_host *ch;
        u32 cl_id;
        time_t cl_connect_time;
+       int setup_done; /* ioctl BLKTRACESETUP done */
        struct io_info *ios;
 };
 
@@ -1083,6 +1084,7 @@ static int setup_buts(void)
                if (ioctl(dpp->fd, BLKTRACESETUP, &buts) >= 0) {
                        dpp->ncpus = max_cpus;
                        dpp->buts_name = strdup(buts.name);
+                       dpp->setup_done = 1;
                        if (dpp->stats)
                                free(dpp->stats);
                        dpp->stats = calloc(dpp->ncpus, sizeof(*dpp->stats));
@@ -1285,7 +1287,8 @@ static void rel_devpaths(void)
                struct devpath *dpp = list_entry(p, struct devpath, head);
 
                list_del(&dpp->head);
-               __stop_trace(dpp->fd);
+               if (dpp->setup_done)
+                       __stop_trace(dpp->fd);
                close(dpp->fd);
 
                if (dpp->heads)