2 files changed, 192 insertions, 13 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 67c1e9a4f812..dba194a8d416 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -847,6 +847,7 @@ fastcall NORET_TYPE void do_exit(long code)
         struct task_struct *tsk = current;
         struct taskstats *tidstats;
         int group_dead;
+        unsigned int mycpu;
 
         profile_task_exit(tsk);
 
@@ -884,7 +885,7 @@ fastcall NORET_TYPE void do_exit(long code)
                                 current->comm, current->pid,
                                 preempt_count());
 
-        taskstats_exit_alloc(&tidstats);
+        taskstats_exit_alloc(&tidstats, &mycpu);
 
         acct_update_integrals(tsk);
         if (tsk->mm) {
@@ -905,7 +906,7 @@ fastcall NORET_TYPE void do_exit(long code)
 #endif
         if (unlikely(tsk->audit_context))
                 audit_free(tsk);
-        taskstats_exit_send(tsk, tidstats, group_dead);
+        taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
         taskstats_exit_free(tidstats);
         delayacct_tsk_exit(tsk);
 
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 4a0a5022b299..abb59e323544 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -19,9 +19,17 @@
 #include <linux/kernel.h>
 #include <linux/taskstats_kern.h>
 #include <linux/delayacct.h>
+#include <linux/cpumask.h>
+#include <linux/percpu.h>
 #include <net/genetlink.h>
 #include <asm/atomic.h>
 
+/*
+ * Maximum length of a cpumask that can be specified in
+ * the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
+ */
+#define TASKSTATS_CPUMASK_MAXLEN        (100+6*NR_CPUS)
+
 static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
 static int family_registered;
 kmem_cache_t *taskstats_cache;
@@ -37,8 +45,25 @@ static struct nla_policy taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1]
 __read_mostly = {
         [TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
         [TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
+        [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
+        [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
+
+struct listener {
+        struct list_head list;
+        pid_t pid;
 };
 
+struct listener_list {
+        struct rw_semaphore sem;
+        struct list_head list;
+};
+static DEFINE_PER_CPU(struct listener_list, listener_array);
+
+enum actions {
+        REGISTER,
+        DEREGISTER,
+        CPU_DONT_CARE
+};
 
 static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
                         void **replyp, size_t size)
@@ -74,25 +99,68 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
         return 0;
 }
 
-static int send_reply(struct sk_buff *skb, pid_t pid, int event)
+/*
+ * Send taskstats data in @skb to listener with nl_pid @pid
+ */
+static int send_reply(struct sk_buff *skb, pid_t pid)
 {
         struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
-        void *reply;
+        void *reply = genlmsg_data(genlhdr);
         int rc;
 
-        reply = genlmsg_data(genlhdr);
-
         rc = genlmsg_end(skb, reply);
         if (rc < 0) {
                 nlmsg_free(skb);
                 return rc;
         }
 
-        if (event == TASKSTATS_MSG_MULTICAST)
-                return genlmsg_multicast(skb, pid, TASKSTATS_LISTEN_GROUP);
         return genlmsg_unicast(skb, pid);
 }
 
+/*
+ * Send taskstats data in @skb to listeners registered for @cpu's exit data
+ */
+static int send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
+{
+        struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
+        struct listener_list *listeners;
+        struct listener *s, *tmp;
+        struct sk_buff *skb_next, *skb_cur = skb;
+        void *reply = genlmsg_data(genlhdr);
+        int rc, ret;
+
+        rc = genlmsg_end(skb, reply);
+        if (rc < 0) {
+                nlmsg_free(skb);
+                return rc;
+        }
+
+        rc = 0;
+        listeners = &per_cpu(listener_array, cpu);
+        down_write(&listeners->sem);
+        list_for_each_entry_safe(s, tmp, &listeners->list, list) {
+                skb_next = NULL;
+                if (!list_is_last(&s->list, &listeners->list)) {
+                        skb_next = skb_clone(skb_cur, GFP_KERNEL);
+                        if (!skb_next) {
+                                nlmsg_free(skb_cur);
+                                rc = -ENOMEM;
+                                break;
+                        }
+                }
+                ret = genlmsg_unicast(skb_cur, s->pid);
+                if (ret == -ECONNREFUSED) {
+                        list_del(&s->list);
+                        kfree(s);
+                        rc = ret;
+                }
+                skb_cur = skb_next;
+        }
+        up_write(&listeners->sem);
+
+        return rc;
+}
+
 static int fill_pid(pid_t pid, struct task_struct *pidtsk,
                 struct taskstats *stats)
 {
@@ -204,8 +272,73 @@ ret:
         return;
 }
 
+static int add_del_listener(pid_t pid, cpumask_t *maskp, int isadd)
+{
+        struct listener_list *listeners;
+        struct listener *s, *tmp;
+        unsigned int cpu;
+        cpumask_t mask = *maskp;
 
-static int taskstats_send_stats(struct sk_buff *skb, struct genl_info *info)
+        if (!cpus_subset(mask, cpu_possible_map))
+                return -EINVAL;
+
+        if (isadd == REGISTER) {
+                for_each_cpu_mask(cpu, mask) {
+                        s = kmalloc_node(sizeof(struct listener), GFP_KERNEL,
+                                         cpu_to_node(cpu));
+                        if (!s)
+                                goto cleanup;
+                        s->pid = pid;
+                        INIT_LIST_HEAD(&s->list);
+
+                        listeners = &per_cpu(listener_array, cpu);
+                        down_write(&listeners->sem);
+                        list_add(&s->list, &listeners->list);
+                        up_write(&listeners->sem);
+                }
+                return 0;
+        }
+
+        /* Deregister or cleanup */
+cleanup:
+        for_each_cpu_mask(cpu, mask) {
+                listeners = &per_cpu(listener_array, cpu);
+                down_write(&listeners->sem);
+                list_for_each_entry_safe(s, tmp, &listeners->list, list) {
+                        if (s->pid == pid) {
+                                list_del(&s->list);
+                                kfree(s);
+                                break;
+                        }
+                }
+                up_write(&listeners->sem);
+        }
+        return 0;
+}
+
+static int parse(struct nlattr *na, cpumask_t *mask)
+{
+        char *data;
+        int len;
+        int ret;
+
+        if (na == NULL)
+                return 1;
+        len = nla_len(na);
+        if (len > TASKSTATS_CPUMASK_MAXLEN)
+                return -E2BIG;
+        if (len < 1)
+                return -EINVAL;
+        data = kmalloc(len, GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+        nla_strlcpy(data, na, len);
+        ret = cpulist_parse(data, *mask);
+        kfree(data);
+        return ret;
+}
+
+static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
 {
         int rc = 0;
         struct sk_buff *rep_skb;
@@ -213,6 +346,19 @@ static int taskstats_send_stats(struct sk_buff *skb, struct genl_info *info)
         void *reply;
         size_t size;
         struct nlattr *na;
+        cpumask_t mask;
+
+        rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], &mask);
+        if (rc < 0)
+                return rc;
+        if (rc == 0)
+                return add_del_listener(info->snd_pid, &mask, REGISTER);
+
+        rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], &mask);
+        if (rc < 0)
+                return rc;
+        if (rc == 0)
+                return add_del_listener(info->snd_pid, &mask, DEREGISTER);
 
         /*
          * Size includes space for nested attributes
@@ -252,7 +398,7 @@ static int taskstats_send_stats(struct sk_buff *skb, struct genl_info *info)
 
         nla_nest_end(rep_skb, na);
 
-        return send_reply(rep_skb, info->snd_pid, TASKSTATS_MSG_UNICAST);
+        return send_reply(rep_skb, info->snd_pid);
 
 nla_put_failure:
         return genlmsg_cancel(rep_skb, reply);
@@ -261,9 +407,35 @@ err:
         return rc;
 }
 
+void taskstats_exit_alloc(struct taskstats **ptidstats, unsigned int *mycpu)
+{
+        struct listener_list *listeners;
+        struct taskstats *tmp;
+        /*
+         * This is the cpu on which the task is exiting currently and will
+         * be the one for which the exit event is sent, even if the cpu
+         * on which this function is running changes later.
+         */
+        *mycpu = raw_smp_processor_id();
+
+        *ptidstats = NULL;
+        tmp = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
+        if (!tmp)
+                return;
+
+        listeners = &per_cpu(listener_array, *mycpu);
+        down_read(&listeners->sem);
+        if (!list_empty(&listeners->list)) {
+                *ptidstats = tmp;
+                tmp = NULL;
+        }
+        up_read(&listeners->sem);
+        kfree(tmp);
+}
+
 /* Send pid data out on exit */
 void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
-                        int group_dead)
+                        int group_dead, unsigned int mycpu)
 {
         int rc;
         struct sk_buff *rep_skb;
@@ -324,7 +496,7 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
         nla_nest_end(rep_skb, na);
 
 send:
-        send_reply(rep_skb, 0, TASKSTATS_MSG_MULTICAST);
+        send_cpu_listeners(rep_skb, mycpu);
         return;
 
 nla_put_failure:
@@ -338,16 +510,22 @@ ret:
 
 static struct genl_ops taskstats_ops = {
         .cmd            = TASKSTATS_CMD_GET,
-        .doit           = taskstats_send_stats,
+        .doit           = taskstats_user_cmd,
         .policy         = taskstats_cmd_get_policy,
 };
 
 /* Needed early in initialization */
 void __init taskstats_init_early(void)
 {
+        unsigned int i;
+
         taskstats_cache = kmem_cache_create("taskstats_cache",
                                                 sizeof(struct taskstats),
                                                 0, SLAB_PANIC, NULL, NULL);
+        for_each_possible_cpu(i) {
+                INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
+                init_rwsem(&(per_cpu(listener_array, i).sem));
+        }
 }
 
 static int __init taskstats_init(void)