Re: [Qemu-devel] [PATCH v4 01/17] util: add helper APIs for dealing with inotify in portable manner

[Bandan Das]

Daniel P. Berrangé <address@hidden> writes:
...
> +
> +int
> +qemu_file_monitor_add_watch(QFileMonitor *mon,
> +                            const char *dirpath,
> +                            const char *filename,
> +                            QFileMonitorHandler cb,
> +                            void *opaque,
> +                            Error **errp)
> +{
> +    QFileMonitorDir *dir;
> +    QFileMonitorWatch watch;
> +    int ret = -1;
> +
> +    qemu_mutex_lock(&mon->lock);
> +    dir = g_hash_table_lookup(mon->dirs, dirpath);
> +    if (!dir) {
> +        int rv = inotify_add_watch(mon->fd, dirpath,
> +                                   IN_CREATE | IN_DELETE | IN_MODIFY |
> +                                   IN_MOVED_TO | IN_MOVED_FROM | IN_ATTRIB);
> +
> +        if (rv < 0) {
> +            error_setg_errno(errp, errno, "Unable to watch '%s'", dirpath);
> +            goto cleanup;
> +        }
> +
> +        trace_qemu_file_monitor_enable_watch(mon, dirpath, rv);
> +
> +        dir = g_new0(QFileMonitorDir, 1);
> +        dir->path = g_strdup(dirpath);
> +        dir->id = rv;
> +        dir->watches = g_array_new(FALSE, TRUE, sizeof(QFileMonitorWatch));
> +
> +        g_hash_table_insert(mon->dirs, dir->path, dir);
> +        g_hash_table_insert(mon->idmap, GINT_TO_POINTER(rv), dir);
> +
> +        if (g_hash_table_size(mon->dirs) == 1) {
> +            qemu_set_fd_handler(mon->fd, qemu_file_monitor_watch, NULL, mon);
> +        }
> +    }
> +
> +    watch.id = dir->nextid++;
> +    watch.filename = g_strdup(filename);
> +    watch.cb = cb;
> +    watch.opaque = opaque;
> +
> +    g_array_append_val(dir->watches, watch);
> +
> +    trace_qemu_file_monitor_add_watch(mon, dirpath,
> +                                      filename ? filename : "<none>",
> +                                      cb, opaque, watch.id);
> +
> +    ret = watch.id;
> +

This seems to break usb-mtp since we are returning watch.id.
Why are we not returning dir->id here ? usb-mtp relies on the watch
descriptor to handle events.

Bandan

> + cleanup:
> +    qemu_mutex_unlock(&mon->lock);
> +    return ret;
> +}
> +