cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper (6678889f) · Commits · e / devices / android_kernel_fairphone_FP5

kernel/cgroup/cgroup-v1.c

+46 −41

Original line number	Diff line number	Diff line
		@@ -1135,7 +1135,15 @@ struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
		.show_path = cgroup_show_path,
		};

		int cgroup1_get_tree(struct fs_context *fc)
		/*
		* The guts of cgroup1 mount - find or create cgroup_root to use.
		* Called with cgroup_mutex held; returns 0 on success, -E... on
		* error and positive - in case when the candidate is busy dying.
		* On success it stashes a reference to cgroup_root into given
		* cgroup_fs_context; that reference is NOT counting towards the
		* cgroup_root refcount.
		*/
		static int cgroup1_root_to_use(struct fs_context *fc)
		{
		struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
		struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
		@@ -1143,16 +1151,10 @@ int cgroup1_get_tree(struct fs_context *fc)
		struct cgroup_subsys *ss;
		int i, ret;

		/* Check if the caller has permission to mount. */
		if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
		return -EPERM;

		cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);

		/* First find the desired set of subsystems */
		ret = check_cgroupfs_options(fc);
		if (ret)
		goto out_unlock;
		return ret;

		/*
		* Destruction of cgroup root is asynchronous, so subsystems may
		@@ -1166,12 +1168,8 @@ int cgroup1_get_tree(struct fs_context *fc)
		ss->root == &cgrp_dfl_root)
		continue;

		if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
		mutex_unlock(&cgroup_mutex);
		msleep(10);
		ret = restart_syscall();
		goto out_free;
		}
		if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt))
		return 1; /* restart */
		cgroup_put(&ss->root->cgrp);
		}

		@@ -1200,16 +1198,14 @@ int cgroup1_get_tree(struct fs_context *fc)
		(ctx->subsys_mask != root->subsys_mask)) {
		if (!name_match)
		continue;
		ret = -EBUSY;
		goto out_unlock;
		return -EBUSY;
		}

		if (root->flags ^ ctx->flags)
		pr_warn("new mount options do not match the existing superblock, will be ignored\n");

		ctx->root = root;
		ret = 0;
		goto out_unlock;
		return 0;
		}

		/*
		@@ -1217,22 +1213,16 @@ int cgroup1_get_tree(struct fs_context *fc)
		* specification is allowed for already existing hierarchies but we
		* can't create new one without subsys specification.
		*/
		if (!ctx->subsys_mask && !ctx->none) {
		ret = cg_invalf(fc, "cgroup1: No subsys list or none specified");
		goto out_unlock;
		}
		if (!ctx->subsys_mask && !ctx->none)
		return cg_invalf(fc, "cgroup1: No subsys list or none specified");

		/* Hierarchies may only be created in the initial cgroup namespace. */
		if (ns != &init_cgroup_ns) {
		ret = -EPERM;
		goto out_unlock;
		}
		if (ns != &init_cgroup_ns)
		return -EPERM;

		root = kzalloc(sizeof(*root), GFP_KERNEL);
		if (!root) {
		ret = -ENOMEM;
		goto out_unlock;
		}
		if (!root)
		return -ENOMEM;

		ctx->root = root;
		init_cgroup_root(ctx);
		@@ -1240,23 +1230,38 @@ int cgroup1_get_tree(struct fs_context *fc)
		ret = cgroup_setup_root(root, ctx->subsys_mask);
		if (ret)
		cgroup_free_root(root);

		out_unlock:
		if (!ret && !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
		mutex_unlock(&cgroup_mutex);
		msleep(10);
		return restart_syscall();
		return ret;
		}

		int cgroup1_get_tree(struct fs_context *fc)
		{
		struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
		struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
		int ret;

		/* Check if the caller has permission to mount. */
		if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
		return -EPERM;

		cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);

		ret = cgroup1_root_to_use(fc);
		if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt))
		ret = 1; /* restart */

		mutex_unlock(&cgroup_mutex);
		out_free:
		if (ret)
		return ret;

		if (!ret)
		ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
		if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {

		if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
		struct super_block *sb = fc->root->d_sb;
		dput(fc->root);
		deactivate_locked_super(sb);
		ret = 1;
		}

		if (unlikely(ret > 0)) {
		msleep(10);
		return restart_syscall();
		}