On Fri, 14 Oct 2022 10:51:36 +0200 Paolo Bonzini <pbonz...@redhat.com> wrote:
> On 10/14/22 08:08, Greg Kurz wrote: > > > > + need_to_open_file = log_flags && !per_thread; > > Pre-existing, but I think this should check log_per_thread instead of > per_thread. > Yes I agree, and also check qemu_loglevel instead of log_flags for the same reason (and to match the comment just above). > > + } else if (filename) { > > + /* > > + * If we are daemonized, we will only log if there is a filename. > > + */ > > + need_to_open_file = true; > > Slightly nicer: > > } else { > /* > * If daemonized, always log to the -D file if present. > */ > need_to_open_file = filename != NULL; > } > Sure. > > @@ -271,10 +276,22 @@ static bool qemu_set_log_internal(const char > > *filename, bool changed_name, > > > > if (!logfile && need_to_open_file) { > > if (filename) { > > - logfile = fopen(filename, log_append ? "a" : "w"); > > + g_autofree char *fname = NULL; > > + > > + /* > > + * If per-thread, filename contains a single %d that should be > > + * converted. > > + */ > > + if (per_thread) { > > + fname = g_strdup_printf(filename, getpid()); > > + } else { > > + fname = g_strdup(filename); > > + } > > + > > + logfile = fopen(fname, log_append ? "a" : "w"); > > if (!logfile) { > > error_setg_errno(errp, errno, "Error opening logfile %s", > > - filename); > > + fname); > > return false; > > } > > /* In case we are a daemon redirect stderr to logfile */ > > This could conflict with the file opened by qemu_log_trylock() when > per-thread logging is enabled *and* QEMU is daemonized. Perhaps > something like: > Yeah... if the main thread happens to call qemu_log(), it then opens a file with the same name indeed. Thanks for catching that ! > 1) change qemu_log_trylock() to > > - if (log_per_thread) { > + if (log_per_thread && log_thread_id() != getpid()) { > > i.e. use the global_file for the main thread > > 2) change qemu_log_unlock() to > > - if (!log_per_thread) { > + if (!thread_file) { > > to match (1) > > 3) change log_thread_id() to something like > > ... > #else > static __thread int my_id = -1; > static int counter; > if (my_id == -1) { > my_id = getpid() + qatomic_fetch_inc(&counter); > } > return my_id; > #endif > > and perhaps do a dummy trylock/unlock late in qemu_set_log_internal(), > to ensure that the main thread is the one with log_thread_id() == getpid()? > > I think this can be a separate patch before this one. > 2) and 3) can certainly be preparatory work but I think 1) should be squashed in my patch. Because of the !per_thread check in need_to_open_file, the existing code in qemu_set_log_internal() doesn't even open the global file and qemu_log_trylock() would always return NULL for the main thread. Thanks for the quick answer and suggestions ! > Paolo >