--- linux-2.4.1/include/linux/proc_fs_i.h	Sat Apr  8 06:38:00 2000
+++ linux-akpm/include/linux/proc_fs_i.h	Fri Feb  2 01:50:40 2001
@@ -1,9 +1,10 @@
 struct proc_inode_info {
 	struct task_struct *task;
 	int type;
-	union {
+	struct {
 		int (*proc_get_link)(struct inode *, struct dentry **, struct vfsmount **);
 		int (*proc_read)(struct task_struct *task, char *page);
+		int (*proc_write)(struct task_struct *task, char *page, size_t nbytes);
 	} op;
 	struct file *file;
 };
--- linux-2.4.1/include/linux/capability.h	Sun Oct 15 01:27:46 2000
+++ linux-akpm/include/linux/capability.h	Fri Feb  2 01:55:00 2001
@@ -231,6 +231,7 @@
 /* Allow enabling/disabling tagged queuing on SCSI controllers and sending
    arbitrary SCSI commands */
 /* Allow setting encryption key on loopback filesystem */
+/* Allow bonding of tasks to CPUs */
 
 #define CAP_SYS_ADMIN        21
 
--- linux-2.4.1/fs/proc/base.c	Tue Nov 21 20:11:21 2000
+++ linux-akpm/fs/proc/base.c	Fri Feb  2 02:41:51 2001
@@ -39,6 +39,8 @@
 int proc_pid_status(struct task_struct*,char*);
 int proc_pid_statm(struct task_struct*,char*);
 int proc_pid_cpu(struct task_struct*,char*);
+int proc_pid_cpus_allowed_read(struct task_struct *task, char * buffer);
+int proc_pid_cpus_allowed_write(struct task_struct *task, char * buffer, size_t nbytes);
 
 static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
 {
@@ -305,8 +307,44 @@
 	return count;
 }
 
+static ssize_t proc_info_write(struct file * file, const char * buf,
+			  size_t count, loff_t *ppos)
+{
+	struct inode * inode = file->f_dentry->d_inode;
+	unsigned long page;
+	ssize_t ret;
+	struct task_struct *task = inode->u.proc_i.task;
+
+	ret = -EINVAL;
+	if (inode->u.proc_i.op.proc_write == NULL)
+		goto out;
+	if (count > PAGE_SIZE - 1)
+		goto out;
+
+	ret = -ENOMEM;
+	if (!(page = __get_free_page(GFP_KERNEL)))
+		goto out;
+
+	ret = -EFAULT;
+	if (copy_from_user((char *)page, buf, count))
+		goto out_free_page;
+
+	((char *)page)[count] = '\0';
+	ret = inode->u.proc_i.op.proc_write(task, (char*)page, count);
+	if (ret < 0)
+		goto out_free_page;
+
+	*ppos += ret;
+
+out_free_page:
+	free_page(page);
+out:
+	return ret;
+}
+
 static struct file_operations proc_info_file_operations = {
 	read:		proc_info_read,
+	write:		proc_info_write,
 };
 
 #define MAY_PTRACE(p) \
@@ -495,6 +533,7 @@
 	PROC_PID_STATM,
 	PROC_PID_MAPS,
 	PROC_PID_CPU,
+	PROC_PID_CPUS_ALLOWED,
 	PROC_PID_FD_DIR = 0x8000,	/* 0x8000-0xffff */
 };
 
@@ -507,7 +550,8 @@
   E(PROC_PID_STAT,	"stat",		S_IFREG|S_IRUGO),
   E(PROC_PID_STATM,	"statm",	S_IFREG|S_IRUGO),
 #ifdef CONFIG_SMP
-  E(PROC_PID_CPU,	"cpu",		S_IFREG|S_IRUGO),
+  E(PROC_PID_CPU,		"cpu",		S_IFREG|S_IRUGO),
+  E(PROC_PID_CPUS_ALLOWED,	"cpus_allowed",	S_IFREG|S_IRUGO|S_IWUSR),
 #endif
   E(PROC_PID_MAPS,	"maps",		S_IFREG|S_IRUGO),
   E(PROC_PID_MEM,	"mem",		S_IFREG|S_IRUSR|S_IWUSR),
@@ -854,6 +894,11 @@
 		case PROC_PID_CPU:
 			inode->i_fop = &proc_info_file_operations;
 			inode->u.proc_i.op.proc_read = proc_pid_cpu;
+			break;
+		case PROC_PID_CPUS_ALLOWED:
+			inode->i_fop = &proc_info_file_operations;
+			inode->u.proc_i.op.proc_read = proc_pid_cpus_allowed_read;
+			inode->u.proc_i.op.proc_write = proc_pid_cpus_allowed_write;
 			break;
 #endif
 		case PROC_PID_MEM:
--- linux-2.4.1/fs/proc/array.c	Tue Nov 21 20:11:21 2000
+++ linux-akpm/fs/proc/array.c	Fri Feb  2 02:05:39 2001
@@ -50,6 +50,8 @@
  * Al Viro & Jeff Garzik :  moved most of the thing into base.c and
  *			 :  proc_misc.c. The rest may eventually go into
  *			 :  base.c too.
+ *
+ * Andrew Morton     : cpus_allowed
  */
 
 #include <linux/config.h>
@@ -695,5 +697,42 @@
 			task->per_cpu_stime[cpu_logical_map(i)]);
 
 	return len;
+}
+
+int proc_pid_cpus_allowed_read(struct task_struct *task, char * buffer)
+{
+	int len;
+
+	len = sprintf(buffer, "%08lx\n", task->cpus_allowed);
+	return len;
+}
+
+/*
+ * FIXME: cpu_online_map should be used, but not all archs have it.
+ */
+
+int proc_pid_cpus_allowed_write(struct task_struct *task, char * buffer, size_t nbytes)
+{
+	unsigned long new_mask;
+	char *endp;
+	int ret;
+	unsigned long flags;
+
+	ret = -EPERM;
+	if (!capable(CAP_SYS_ADMIN))
+		goto out;
+
+	new_mask = simple_strtoul(buffer, &endp, 16);
+	ret = endp - buffer;
+
+	spin_lock_irqsave(&runqueue_lock, flags);	/* token effort to not be racy */
+	if ((((1 << smp_num_cpus) - 1) & new_mask) == 0)
+		ret = -EINVAL;
+	else
+		task->cpus_allowed = new_mask;
+	spin_unlock_irqrestore(&runqueue_lock, flags);
+
+out:
+	return ret;
 }
 #endif