Jeff Mahoney <je...@suse.com> writes: > There's a bug in the blktrace client where it will stop and tear down > all of the tracing instances for devices it's opened whether it > successfully completed the setup or not. > > By starting multiple blktrace processes on the same device, it's possible > to permanently disable blktrace on that device. The cause is that when > the first blktrace process to exit tears down the directory structure, > the trace files are still held open. Debugfs removes the dentries for the > open files just fine but the relay implementation doesn't remove the > dentries until all of the references to the file are dropped. This means > that if there are open files when debugfs_remove is called for the device > directory, the directory is not empty and can't be removed. Since the > shutdown of the blktrace structure xchg's the structure out, there's no > way to clean up the directory and any new blktrace processes will fail > to start because it can't create the directory. > > This patch adds a kref to blk_trace so that we can release it after the > initial reference as well as all of the references accumulated by the > relay files are dropped.
Can't we just do proper unwinding of errors in the do_blktrace_setup function? In other words, don't just blindly call blk_trace_free, but instead just undo anything we've done. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
