blktrace: avoid device duplication

Fixup for bz 501457.

Problem:
If the device list file contains the same device
as supplied on the command line, blktrace stops
immediately and further I/O tracing is impossible.

Bug: device duplication in the devpaths ends with
programm termination (BLKTRACESETUP ioctl returns
error) while resources (open files in debugfs) are
not released.

Solution:
Make sure devices are not duplicated in devpaths
pool.

Signed-off-by: Edward Shishkin <edward@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/blktrace.c b/blktrace.c
index b4c919d..a67e1b8 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -1200,8 +1200,17 @@ static int add_devpath(char *path)
 {
 	int fd;
 	struct devpath *dpp;
+	struct list_head *p;
 
 	/*
+	 * Verify device is not duplicated
+	 */
+	__list_for_each(p, &devpaths) {
+	       struct devpath *tmp = list_entry(p, struct devpath, head);
+	       if (!strcmp(tmp->path, path))
+		        return 0;
+	}
+	/*
 	 * Verify device is valid before going too far
 	 */
 	fd = my_open(path, O_RDONLY | O_NONBLOCK);