From 1836be5d99c9362f1e2b39206c95270f19cb7faa Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Wed, 5 Jun 2024 23:07:27 -0500 Subject: [PATCH] fix hang when BLKTRACESETUP fails and "-o -" is used # blktrace -o - /dev/sda /dev/sdb /dev/sdc has to be SIGKILLed if BLKTRACESETUP fails for any or all of the devices listed. (I simulated this by just catching one of the devices in setup_buts(), skipping the ioctl, and doing ret++). This seems to be because with "-o -" on the command line, use_tracer_devpaths() sees piped_output set, so we call process_trace_bufs which ends up waiting on (!done) and "done" is never set. i.e. atexit(exit_tracing) wait_tracers if (use_tracer_devpaths()) // true because "-o -" process_trace_bufs while (wait_empty_entries()) wait_empty_entries while (!done ... ) I think this can be avoided by just setting "done = 1" before returning when setup_buts() fails in run_tracers(). Signed-off-by: Eric Sandeen Reviewed-by: Jeff Moyer Link: https://lore.kernel.org/r/f3204c9d-1384-40b5-a5fb-3bb967ca2bec@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Pavel Reichl --- blktrace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/blktrace.c b/blktrace.c index 3444fbb..038b2cb 100644 --- a/blktrace.c +++ b/blktrace.c @@ -2684,8 +2684,10 @@ static int run_tracers(void) if (net_mode == Net_client) printf("blktrace: connecting to %s\n", hostname); - if (setup_buts()) + if (setup_buts()) { + done = 1; return 1; + } if (use_tracer_devpaths()) { if (setup_tracer_devpaths()) -- 2.46.0