X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fcpuset.c;h=824b1c01f4107667abb7d0e4e8923678a15966c4;hb=94f6030ca792c57422f04a73e7a872d8325946d3;hp=d240349cbf0f282d56e12205b68d19ecce215b40;hpb=5f757f91e70a97eda8f0cc13bddc853209b2d173;p=linux-2.6-omap-h63xx.git

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index d240349cbf0..824b1c01f41 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -42,7 +42,6 @@
 #include <linux/seq_file.h>
 #include <linux/security.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/spinlock.h>
 #include <linux/stat.h>
 #include <linux/string.h>
@@ -822,11 +821,22 @@ static int update_cpumask(struct cpuset *cs, char *buf)
 		return -EACCES;
 
 	trialcs = *cs;
-	retval = cpulist_parse(buf, trialcs.cpus_allowed);
-	if (retval < 0)
-		return retval;
+
+	/*
+	 * 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.
+	 */
+	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+		cpus_clear(trialcs.cpus_allowed);
+	} else {
+		retval = cpulist_parse(buf, trialcs.cpus_allowed);
+		if (retval < 0)
+			return retval;
+	}
 	cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
-	if (cpus_empty(trialcs.cpus_allowed))
+	/* cpus_allowed cannot be empty for a cpuset with attached tasks. */
+	if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed))
 		return -ENOSPC;
 	retval = validate_change(cs, &trialcs);
 	if (retval < 0)
@@ -919,16 +929,27 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 		return -EACCES;
 
 	trialcs = *cs;
-	retval = nodelist_parse(buf, trialcs.mems_allowed);
-	if (retval < 0)
-		goto done;
+
+	/*
+	 * 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.
+	 */
+	if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+		nodes_clear(trialcs.mems_allowed);
+	} else {
+		retval = nodelist_parse(buf, trialcs.mems_allowed);
+		if (retval < 0)
+			goto done;
+	}
 	nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
 	oldmem = cs->mems_allowed;
 	if (nodes_equal(oldmem, trialcs.mems_allowed)) {
 		retval = 0;		/* Too easy - nothing to do */
 		goto done;
 	}
-	if (nodes_empty(trialcs.mems_allowed)) {
+	/* mems_allowed cannot be empty for a cpuset with attached tasks. */
+	if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) {
 		retval = -ENOSPC;
 		goto done;
 	}
@@ -960,10 +981,10 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 		mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
 		if (!mmarray)
 			goto done;
-		write_lock_irq(&tasklist_lock);		/* block fork */
+		read_lock(&tasklist_lock);		/* block fork */
 		if (atomic_read(&cs->count) <= ntasks)
 			break;				/* got enough */
-		write_unlock_irq(&tasklist_lock);	/* try again */
+		read_unlock(&tasklist_lock);		/* try again */
 		kfree(mmarray);
 	}
 
@@ -985,7 +1006,7 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 			continue;
 		mmarray[n++] = mm;
 	} while_each_thread(g, p);
-	write_unlock_irq(&tasklist_lock);
+	read_unlock(&tasklist_lock);
 
 	/*
 	 * Now that we've dropped the tasklist spinlock, we can
@@ -1661,9 +1682,9 @@ static int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs)
 
 	do_each_thread(g, p) {
 		if (p->cpuset == cs) {
-			pidarray[n++] = p->pid;
 			if (unlikely(n == npids))
 				goto array_full;
+			pidarray[n++] = p->pid;
 		}
 	} while_each_thread(g, p);
 
@@ -1751,12 +1772,7 @@ static ssize_t cpuset_tasks_read(struct file *file, char __user *buf,
 {
 	struct ctr_struct *ctr = file->private_data;
 
-	if (*ppos + nbytes > ctr->bufsz)
-		nbytes = ctr->bufsz - *ppos;
-	if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
-		return -EFAULT;
-	*ppos += nbytes;
-	return nbytes;
+	return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz);
 }
 
 static int cpuset_tasks_release(struct inode *unused_inode, struct file *file)
@@ -2200,10 +2216,6 @@ void cpuset_fork(struct task_struct *child)
  * it is holding that mutex while calling check_for_release(),
  * which calls kmalloc(), so can't be called holding callback_mutex().
  *
- * We don't need to task_lock() this reference to tsk->cpuset,
- * because tsk is already marked PF_EXITING, so attach_task() won't
- * mess with it, or task is a failed fork, never visible to attach_task.
- *
  * the_top_cpuset_hack:
  *
  *    Set the exiting tasks cpuset to the root cpuset (top_cpuset).
@@ -2242,8 +2254,10 @@ void cpuset_exit(struct task_struct *tsk)
 {
 	struct cpuset *cs;
 
+	task_lock(current);
 	cs = tsk->cpuset;
 	tsk->cpuset = &top_cpuset;	/* the_top_cpuset_hack - see above */
+	task_unlock(current);
 
 	if (notify_on_release(cs)) {
 		char *pathbuf = NULL;