On Thu, 8 Sep 2016, Fenghua Yu wrote:
> +static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
> + .mkdir = rdtgroup_mkdir,
> + .rmdir = rdtgroup_rmdir,
> +};
> +
> +static struct file_system_type rdt_fs_type = {
> + .name = "resctrl",
> + .mount = rdt_mount,
> + .kill_sb = rdt_kill_sb,
> +};
So the above struct is nicely aligned and readable. While this one is
not. Sigh,
> struct rdtgroup *root_rdtgrp;
> static struct rftype rdtgroup_partition_base_files[];
> struct cache_domain cache_domains[MAX_CACHE_LEAVES];
> /* The default hierarchy. */
> struct rdtgroup_root rdtgrp_dfl_root;
> static struct list_head rdtgroups;
> +bool rdtgroup_mounted;
Your choice of global/static visible variables is driven by a random
generator or what?
> /*
> * kernfs_root - find out the kernfs_root a kernfs_node belongs to
> @@ -730,6 +749,110 @@ static void rdtgroup_destroy_locked(struct rdtgroup
> *rdtgrp)
> kernfs_remove(rdtgrp->kn);
> }
>
> +static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
> + umode_t mode)
> +{
> + struct rdtgroup *parent, *rdtgrp;
> + struct rdtgroup_root *root;
> + struct kernfs_node *kn;
> + int ret;
> +
> + if (parent_kn != root_rdtgrp->kn)
> + return -EPERM;
> +
> + /* Do not accept '\n' to avoid unparsable situation.
> + */
Where did copy you this comment style from? Its' horrible and here is a
lengthy explanation why: https://lkml.org/lkml/2016/7/8/625
> +static struct dentry *rdt_mount(struct file_system_type *fs_type,
> + int flags, const char *unused_dev_name,
> + void *data)
> +{
> + struct super_block *pinned_sb = NULL;
> + struct rdtgroup_root *root;
> + struct dentry *dentry;
> + int ret;
> + bool new_sb;
> +
> + /*
> + * The first time anyone tries to mount a rdtgroup, enable the list
> + * linking tasks and fix up all existing tasks.
What are 'list linking tasks'? What is fixed up here?
> + */
> + if (rdtgroup_mounted)
> + return ERR_PTR(-EBUSY);
How is this serialized against concurrent mounts? Oh well....
> + rdt_opts.cdp_enabled = false;
> + rdt_opts.verbose = false;
> + cdp_enabled = false;
> +
> + ret = parse_rdtgroupfs_options(data);
> + if (ret)
> + goto out_mount;
> +
> + if (rdt_opts.cdp_enabled) {
> + cdp_enabled = true;
> + cconfig.max_closid >>= cdp_enabled;
> + pr_info("CDP is enabled\n");
> + }
> +
> + init_msrs(cdp_enabled);
> +
> + root = &rdtgrp_dfl_root;
> +
> + ret = get_default_resources(&root->rdtgrp);
> + if (ret)
> + return ERR_PTR(-ENOSPC);
> +
> +out_mount:
> + dentry = kernfs_mount(fs_type, flags, root->kf_root,
> + RDTGROUP_SUPER_MAGIC,
> + &new_sb);
> + if (IS_ERR(dentry) || !new_sb)
> + goto out_unlock;
And ret , which is returned @out_unlock is 0. So instead of returning the
error code encoded in dentry you return a NULL pointer.
> + /*
> + * If @pinned_sb, we're reusing an existing root and holding an
> + * extra ref on its sb. Mount is complete. Put the extra ref.
> + */
> + if (pinned_sb) {
And how exactly becomes pinned_sb != NULL?
> + WARN_ON(new_sb);
> + deactivate_super(pinned_sb);
> + }
Not at all.
> + INIT_LIST_HEAD(&root->rdtgrp.pset.tasks);
> +
> + cpumask_copy(&root->rdtgrp.cpu_mask, cpu_online_mask);
> + static_key_slow_inc(&rdt_enable_key);
> + rdtgroup_mounted = true;
> +
> + return dentry;
> +
> +out_unlock:
> + return ERR_PTR(ret);
So a return magically unlocks stuff. Or does this happen in ERR_PTR()?
This jump label is not only pointless it's also named badly.
Thanks,
tglx
