cpusets: decrustify cpuset mask update code

Decrustify the kernel/cpuset.c 'cpus' and 'mems' updating code.

Other than subtle improvements in the consistency of identifying
white space at the beginning and end of passed in masks, this
doesn't make any visible difference in behaviour.  But it's
one or two hundred kernel text bytes smaller, and easier to
understand.

[akpm@linux-foundation.org: coding-style fix]
Signed-off-by: NPaul Jackson <pj@sgi.com>
Reviewed-by: NPaul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/cpuset.c

@@ -488,6 +488,14 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
 			return -EINVAL;
 	}
 
+	/* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
+	if (cgroup_task_count(cur->css.cgroup)) {
+		if (cpus_empty(trial->cpus_allowed) ||
+		    nodes_empty(trial->mems_allowed)) {
+			return -ENOSPC;
+		}
+	}
+
 	return 0;
 }
 
@@ -710,11 +718,13 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 	trialcs = *cs;
 
 	/*
-	 * We allow a cpuset's cpus_allowed to be empty; if it has attached
-	 * tasks, we'll catch it later when we validate the change and return
-	 * -ENOSPC.
+	 * An empty cpus_allowed is ok iff there are no tasks in the cpuset.
+	 * Since cpulist_parse() fails on an empty mask, we special case
+	 * that parsing.  The validate_change() call ensures that cpusets
+	 * with tasks have cpus.
 	 */
-	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+	buf = strstrip(buf);
+	if (!*buf) {
 		cpus_clear(trialcs.cpus_allowed);
 	} else {
 		retval = cpulist_parse(buf, trialcs.cpus_allowed);
@@ -722,10 +732,6 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 			return retval;
 	}
 	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
-	/* cpus_allowed cannot be empty for a cpuset with attached tasks. */
-	if (cgroup_task_count(cs->css.cgroup) &&
-	    cpus_empty(trialcs.cpus_allowed))
-		return -ENOSPC;
 	retval = validate_change(cs, &trialcs);
 	if (retval < 0)
 		return retval;
@@ -830,29 +836,19 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 	trialcs = *cs;
 
 	/*
-	 * We allow a cpuset's mems_allowed to be empty; if it has attached
-	 * tasks, we'll catch it later when we validate the change and return
-	 * -ENOSPC.
+	 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
+	 * Since nodelist_parse() fails on an empty mask, we special case
+	 * that parsing.  The validate_change() call ensures that cpusets
+	 * with tasks have memory.
 	 */
-	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+	buf = strstrip(buf);
+	if (!*buf) {
 		nodes_clear(trialcs.mems_allowed);
 	} else {
 		retval = nodelist_parse(buf, trialcs.mems_allowed);
 		if (retval < 0)
 			goto done;
-		if (!nodes_intersects(trialcs.mems_allowed,
-						node_states[N_HIGH_MEMORY])) {
-			/*
-			 * error if only memoryless nodes specified.
-			 */
-			retval = -ENOSPC;
-			goto done;
-		}
 	}
-	/*
-	 * Exclude memoryless nodes.  We know that trialcs.mems_allowed
-	 * contains at least one node with memory.
-	 */
 	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed,
 						node_states[N_HIGH_MEMORY]);
 	oldmem = cs->mems_allowed;
@@ -860,12 +856,6 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 		retval = 0;		/* Too easy - nothing to do */
 		goto done;
 	}
-	/* mems_allowed cannot be empty for a cpuset with attached tasks. */
-	if (cgroup_task_count(cs->css.cgroup) &&
-	    nodes_empty(trialcs.mems_allowed)) {
-		retval = -ENOSPC;
-		goto done;
-	}
 	retval = validate_change(cs, &trialcs);
 	if (retval < 0)
 		goto done;