[RFC] [PATCH 11/12] Add members file support to RCFS

[sekharan@us.ibm.com]

11/12 - ckrm_configfs_rcfs_members

Adds attr_store and attr_show support for members file.
--

Signed-Off-By: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-Off-By: Shailabh Nagar <nagar@watson.ibm.com>
Signed-Off-By: Matt Helsley <matthltc@us.ibm.com>

 kernel/ckrm/ckrm_rcfs.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 49 insertions(+)

Index: linux2617-rc2/kernel/ckrm/ckrm_rcfs.c
===================================================================
--- linux2617-rc2.orig/kernel/ckrm/ckrm_rcfs.c
+++ linux2617-rc2/kernel/ckrm/ckrm_rcfs.c
@@ -244,6 +244,43 @@ static ssize_t show_shares(struct ckrm_c
 	return rc;
 }
 
+/*
+ * Given a buffer with a pid in it, add the task with that pid to the class.
+ * Ignores entire buffer after the first pid is parsed.
+ */
+static int add_member(struct ckrm_class *class, const char *str)
+{
+	pid_t pid;
+
+	pid = (pid_t) simple_strtol(str, NULL, 0);
+	if (pid <= 0)
+		return -EINVAL; /* Not a valid pid */
+	return ckrm_setclass(pid, class);
+}
+
+/*
+ * Lists pids of tasks that belong to the given class.
+ */
+static ssize_t show_members(struct ckrm_class *class, char *buf)
+{
+	ssize_t i, rc = 0, bufsize = PAGE_SIZE;
+	struct task_struct *tsk;
+
+	spin_lock(&class->class_lock);
+	list_for_each_entry(tsk, &class->task_list, member_list) {
+		if (bufsize <= 0) {
+			rc = -ENOSPC;
+			break;
+		}
+		if (!tsk->pid)	/* Ignore swappers */
+			continue;
+		i = snprintf(buf, bufsize, "%ld\n", (long)tsk->pid);
+		buf += i; rc += i; bufsize -= i;
+	}
+	spin_unlock(&class->class_lock);
+	return rc;
+}
+
 struct class_attribute {
 	struct configfs_attribute configfs_attr;
 	ssize_t (*show)(struct ckrm_class *, char *);
@@ -270,6 +307,17 @@ struct class_attribute shares_attr = {
 	.store = set_shares
 };
 
+struct class_attribute members_attr = {
+	.configfs_attr = {
+		.ca_name = "members",
+		.ca_owner = THIS_MODULE,
+		.ca_mode = S_IRUGO | S_IWUSR
+	},
+	.show = show_members,
+	.store = add_member
+};
+
+
 static struct configfs_subsystem rcfs_subsys;
 static struct config_item_type rcfs_class_type;
 
@@ -415,6 +463,7 @@ static struct configfs_group_operations 
 static struct configfs_attribute *class_attrs[] = {
 	&stats_attr.configfs_attr,
 	&shares_attr.configfs_attr,
+	&members_attr.configfs_attr,
 	NULL
 };
 

-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
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