sched: clean up some control group code

- replace "cont" with "cgrp" in a few places in the CFS cgroup code, 
- use write_uint rather than write for cpu.shares write function
Signed-off-by: Paul Menage <menage@google.com>
Acked-by : Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -7124,25 +7124,25 @@ unsigned long sched_group_shares(struct task_group *tg)
 #ifdef CONFIG_FAIR_CGROUP_SCHED
 
 /* return corresponding task_group object of a cgroup */
-static inline struct task_group *cgroup_tg(struct cgroup *cont)
+static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
 {
-	return container_of(cgroup_subsys_state(cont, cpu_cgroup_subsys_id),
-					 struct task_group, css);
+	return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id),
+			    struct task_group, css);
 }
 
 static struct cgroup_subsys_state *
-cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
+cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
 {
 	struct task_group *tg;
 
-	if (!cont->parent) {
+	if (!cgrp->parent) {
 		/* This is early initialization for the top cgroup */
-		init_task_group.css.cgroup = cont;
+		init_task_group.css.cgroup = cgrp;
 		return &init_task_group.css;
 	}
 
 	/* we support only 1-level deep hierarchical scheduler atm */
-	if (cont->parent->parent)
+	if (cgrp->parent->parent)
 		return ERR_PTR(-EINVAL);
 
 	tg = sched_create_group();
@@ -7150,21 +7150,21 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 		return ERR_PTR(-ENOMEM);
 
 	/* Bind the cgroup to task_group object we just created */
-	tg->css.cgroup = cont;
+	tg->css.cgroup = cgrp;
 
 	return &tg->css;
 }
 
 static void cpu_cgroup_destroy(struct cgroup_subsys *ss,
-					struct cgroup *cont)
+			       struct cgroup *cgrp)
 {
-	struct task_group *tg = cgroup_tg(cont);
+	struct task_group *tg = cgroup_tg(cgrp);
 
 	sched_destroy_group(tg);
 }
 
 static int cpu_cgroup_can_attach(struct cgroup_subsys *ss,
-			     struct cgroup *cont, struct task_struct *tsk)
+			     struct cgroup *cgrp, struct task_struct *tsk)
 {
 	/* We don't support RT-tasks being in separate groups */
 	if (tsk->sched_class != &fair_sched_class)
@@ -7174,38 +7174,21 @@ static int cpu_cgroup_can_attach(struct cgroup_subsys *ss,
 }
 
 static void
-cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cont,
+cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
 			struct cgroup *old_cont, struct task_struct *tsk)
 {
 	sched_move_task(tsk);
 }
 
-static ssize_t cpu_shares_write(struct cgroup *cont, struct cftype *cftype,
-				struct file *file, const char __user *userbuf,
-				size_t nbytes, loff_t *ppos)
+static int cpu_shares_write_uint(struct cgroup *cgrp, struct cftype *cftype,
+				u64 shareval)
 {
-	unsigned long shareval;
-	struct task_group *tg = cgroup_tg(cont);
-	char buffer[2*sizeof(unsigned long) + 1];
-	int rc;
-
-	if (nbytes > 2*sizeof(unsigned long))	/* safety check */
-		return -E2BIG;
-
-	if (copy_from_user(buffer, userbuf, nbytes))
-		return -EFAULT;
-
-	buffer[nbytes] = 0;	/* nul-terminate */
-	shareval = simple_strtoul(buffer, NULL, 10);
-
-	rc = sched_group_set_shares(tg, shareval);
-
-	return (rc < 0 ? rc : nbytes);
+	return sched_group_set_shares(cgroup_tg(cgrp), shareval);
 }
 
-static u64 cpu_shares_read_uint(struct cgroup *cont, struct cftype *cft)
+static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft)
 {
-	struct task_group *tg = cgroup_tg(cont);
+	struct task_group *tg = cgroup_tg(cgrp);
 
 	return (u64) tg->shares;
 }
@@ -7213,7 +7196,7 @@ static u64 cpu_shares_read_uint(struct cgroup *cont, struct cftype *cft)
 static struct cftype cpu_shares = {
 	.name = "shares",
 	.read_uint = cpu_shares_read_uint,
-	.write = cpu_shares_write,
+	.write_uint = cpu_shares_write_uint,
 };
 
 static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)