1 files changed, 39 insertions, 48 deletions

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 5d6a8c54ee85..f45c5e70773c 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -77,7 +77,8 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
         /*
          * If new attributes are added, please revisit this allocation
          */
-        skb = nlmsg_new(genlmsg_total_size(size), GFP_KERNEL);
+        size = nlmsg_total_size(genlmsg_total_size(size));
+        skb = nlmsg_new(size, GFP_KERNEL);
         if (!skb)
                 return -ENOMEM;
 
@@ -174,21 +175,19 @@ static void send_cpu_listeners(struct sk_buff *skb, unsigned int cpu)
         up_write(&listeners->sem);
 }
 
-static int fill_pid(pid_t pid, struct task_struct *pidtsk,
+static int fill_pid(pid_t pid, struct task_struct *tsk,
                 struct taskstats *stats)
 {
         int rc = 0;
-        struct task_struct *tsk = pidtsk;
 
-        if (!pidtsk) {
-                read_lock(&tasklist_lock);
+        if (!tsk) {
+                rcu_read_lock();
                 tsk = find_task_by_pid(pid);
-                if (!tsk) {
-                        read_unlock(&tasklist_lock);
+                if (tsk)
+                        get_task_struct(tsk);
+                rcu_read_unlock();
+                if (!tsk)
                         return -ESRCH;
-                }
-                get_task_struct(tsk);
-                read_unlock(&tasklist_lock);
         } else
                 get_task_struct(tsk);
 
@@ -214,39 +213,30 @@ static int fill_pid(pid_t pid, struct task_struct *pidtsk,
 
 }
 
-static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
+static int fill_tgid(pid_t tgid, struct task_struct *first,
                 struct taskstats *stats)
 {
-        struct task_struct *tsk, *first;
+        struct task_struct *tsk;
         unsigned long flags;
+        int rc = -ESRCH;
 
         /*
          * Add additional stats from live tasks except zombie thread group
          * leaders who are already counted with the dead tasks
          */
-        first = tgidtsk;
-        if (!first) {
-                read_lock(&tasklist_lock);
+        rcu_read_lock();
+        if (!first)
                 first = find_task_by_pid(tgid);
-                if (!first) {
-                        read_unlock(&tasklist_lock);
-                        return -ESRCH;
-                }
-                get_task_struct(first);
-                read_unlock(&tasklist_lock);
-        } else
-                get_task_struct(first);
 
-        /* Start with stats from dead tasks */
-        spin_lock_irqsave(&first->signal->stats_lock, flags);
+        if (!first || !lock_task_sighand(first, &flags))
+                goto out;
+
         if (first->signal->stats)
                 memcpy(stats, first->signal->stats, sizeof(*stats));
-        spin_unlock_irqrestore(&first->signal->stats_lock, flags);
 
         tsk = first;
-        read_lock(&tasklist_lock);
         do {
-                if (tsk->exit_state == EXIT_ZOMBIE && thread_group_leader(tsk))
+                if (tsk->exit_state)
                         continue;
                 /*
                  * Accounting subsystem can call its functions here to
@@ -257,15 +247,18 @@ static int fill_tgid(pid_t tgid, struct task_struct *tgidtsk,
                 delayacct_add_tsk(stats, tsk);
 
         } while_each_thread(first, tsk);
-        read_unlock(&tasklist_lock);
-        stats->version = TASKSTATS_VERSION;
 
+        unlock_task_sighand(first, &flags);
+        rc = 0;
+out:
+        rcu_read_unlock();
+
+        stats->version = TASKSTATS_VERSION;
         /*
          * Accounting subsytems can also add calls here to modify
          * fields of taskstats.
          */
-
-        return 0;
+        return rc;
 }
 
 
@@ -273,7 +266,7 @@ static void fill_tgid_exit(struct task_struct *tsk)
 {
         unsigned long flags;
 
-        spin_lock_irqsave(&tsk->signal->stats_lock, flags);
+        spin_lock_irqsave(&tsk->sighand->siglock, flags);
         if (!tsk->signal->stats)
                 goto ret;
 
@@ -285,7 +278,7 @@ static void fill_tgid_exit(struct task_struct *tsk)
          */
         delayacct_add_tsk(tsk->signal->stats, tsk);
 ret:
-        spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
+        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
         return;
 }
 
@@ -419,7 +412,7 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
         return send_reply(rep_skb, info->snd_pid);
 
 nla_put_failure:
-        return genlmsg_cancel(rep_skb, reply);
+        rc = genlmsg_cancel(rep_skb, reply);
 err:
         nlmsg_free(rep_skb);
         return rc;
@@ -461,24 +454,26 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
         size_t size;
         int is_thread_group;
         struct nlattr *na;
-        unsigned long flags;
 
-        if (!family_registered || !tidstats)
+        if (!family_registered)
                 return;
 
-        spin_lock_irqsave(&tsk->signal->stats_lock, flags);
-        is_thread_group = tsk->signal->stats ? 1 : 0;
-        spin_unlock_irqrestore(&tsk->signal->stats_lock, flags);
-
-        rc = 0;
         /*
          * Size includes space for nested attributes
          */
         size = nla_total_size(sizeof(u32)) +
                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
 
-        if (is_thread_group)
-                size = 2 * size;        /* PID + STATS + TGID + STATS */
+        is_thread_group = (tsk->signal->stats != NULL);
+        if (is_thread_group) {
+                /* PID + STATS + TGID + STATS */
+                size = 2 * size;
+                /* fill the tsk->signal->stats structure */
+                fill_tgid_exit(tsk);
+        }
+
+        if (!tidstats)
+                return;
 
         rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
         if (rc < 0)
@@ -498,11 +493,8 @@ void taskstats_exit_send(struct task_struct *tsk, struct taskstats *tidstats,
                 goto send;
 
         /*
-         * tsk has/had a thread group so fill the tsk->signal->stats structure
          * Doesn't matter if tsk is the leader or the last group member leaving
          */
-
-        fill_tgid_exit(tsk);
         if (!group_dead)
                 goto send;
 
@@ -519,7 +511,6 @@ send:
 
 nla_put_failure:
         genlmsg_cancel(rep_skb, reply);
-        goto ret;
 err_skb:
         nlmsg_free(rep_skb);
 ret: