1 files changed, 136 insertions, 69 deletions

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 11281d5792bd..3308fd7f1b52 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -175,22 +175,8 @@ static void send_cpu_listeners(struct sk_buff *skb,
         up_write(&listeners->sem);
 }
 
-static int fill_pid(pid_t pid, struct task_struct *tsk,
-                struct taskstats *stats)
+static void fill_stats(struct task_struct *tsk, struct taskstats *stats)
 {
-        int rc = 0;
-
-        if (!tsk) {
-                rcu_read_lock();
-                tsk = find_task_by_vpid(pid);
-                if (tsk)
-                        get_task_struct(tsk);
-                rcu_read_unlock();
-                if (!tsk)
-                        return -ESRCH;
-        } else
-                get_task_struct(tsk);
-
         memset(stats, 0, sizeof(*stats));
         /*
          * Each accounting subsystem adds calls to its functions to
@@ -209,17 +195,27 @@ static int fill_pid(pid_t pid, struct task_struct *tsk,
 
         /* fill in extended acct fields */
         xacct_add_tsk(stats, tsk);
+}
 
-        /* Define err: label here if needed */
-        put_task_struct(tsk);
-        return rc;
+static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
+{
+        struct task_struct *tsk;
 
+        rcu_read_lock();
+        tsk = find_task_by_vpid(pid);
+        if (tsk)
+                get_task_struct(tsk);
+        rcu_read_unlock();
+        if (!tsk)
+                return -ESRCH;
+        fill_stats(tsk, stats);
+        put_task_struct(tsk);
+        return 0;
 }
 
-static int fill_tgid(pid_t tgid, struct task_struct *first,
-                struct taskstats *stats)
+static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
 {
-        struct task_struct *tsk;
+        struct task_struct *tsk, *first;
         unsigned long flags;
         int rc = -ESRCH;
 
@@ -228,8 +224,7 @@ static int fill_tgid(pid_t tgid, struct task_struct *first,
          * leaders who are already counted with the dead tasks
          */
         rcu_read_lock();
-        if (!first)
-                first = find_task_by_vpid(tgid);
+        first = find_task_by_vpid(tgid);
 
         if (!first || !lock_task_sighand(first, &flags))
                 goto out;
@@ -268,7 +263,6 @@ out:
         return rc;
 }
 
-
 static void fill_tgid_exit(struct task_struct *tsk)
 {
         unsigned long flags;
@@ -355,6 +349,10 @@ static int parse(struct nlattr *na, struct cpumask *mask)
         return ret;
 }
 
+#ifdef CONFIG_IA64
+#define TASKSTATS_NEEDS_PADDING 1
+#endif
+
 static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
 {
         struct nlattr *na, *ret;
@@ -364,9 +362,33 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
                         ? TASKSTATS_TYPE_AGGR_PID
                         : TASKSTATS_TYPE_AGGR_TGID;
 
+        /*
+         * The taskstats structure is internally aligned on 8 byte
+         * boundaries but the layout of the aggregrate reply, with
+         * two NLA headers and the pid (each 4 bytes), actually
+         * force the entire structure to be unaligned. This causes
+         * the kernel to issue unaligned access warnings on some
+         * architectures like ia64. Unfortunately, some software out there
+         * doesn't properly unroll the NLA packet and assumes that the start
+         * of the taskstats structure will always be 20 bytes from the start
+         * of the netlink payload. Aligning the start of the taskstats
+         * structure breaks this software, which we don't want. So, for now
+         * the alignment only happens on architectures that require it
+         * and those users will have to update to fixed versions of those
+         * packages. Space is reserved in the packet only when needed.
+         * This ifdef should be removed in several years e.g. 2012 once
+         * we can be confident that fixed versions are installed on most
+         * systems. We add the padding before the aggregate since the
+         * aggregate is already a defined type.
+         */
+#ifdef TASKSTATS_NEEDS_PADDING
+        if (nla_put(skb, TASKSTATS_TYPE_NULL, 0, NULL) < 0)
+                goto err;
+#endif
         na = nla_nest_start(skb, aggr);
         if (!na)
                 goto err;
+
         if (nla_put(skb, type, sizeof(pid), &pid) < 0)
                 goto err;
         ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
@@ -424,74 +446,122 @@ err:
         return rc;
 }
 
-static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
+static int cmd_attr_register_cpumask(struct genl_info *info)
 {
-        int rc;
-        struct sk_buff *rep_skb;
-        struct taskstats *stats;
-        size_t size;
         cpumask_var_t mask;
+        int rc;
 
         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                 return -ENOMEM;
-
         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
         if (rc < 0)
-                goto free_return_rc;
-        if (rc == 0) {
-                rc = add_del_listener(info->snd_pid, mask, REGISTER);
-                goto free_return_rc;
-        }
+                goto out;
+        rc = add_del_listener(info->snd_pid, mask, REGISTER);
+out:
+        free_cpumask_var(mask);
+        return rc;
+}
+
+static int cmd_attr_deregister_cpumask(struct genl_info *info)
+{
+        cpumask_var_t mask;
+        int rc;
 
+        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+                return -ENOMEM;
         rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
         if (rc < 0)
-                goto free_return_rc;
-        if (rc == 0) {
-                rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
-free_return_rc:
-                free_cpumask_var(mask);
-                return rc;
-        }
+                goto out;
+        rc = add_del_listener(info->snd_pid, mask, DEREGISTER);
+out:
         free_cpumask_var(mask);
+        return rc;
+}
+
+static size_t taskstats_packet_size(void)
+{
+        size_t size;
 
-        /*
-         * Size includes space for nested attributes
-         */
         size = nla_total_size(sizeof(u32)) +
                 nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
+#ifdef TASKSTATS_NEEDS_PADDING
+        size += nla_total_size(0); /* Padding for alignment */
+#endif
+        return size;
+}
+
+static int cmd_attr_pid(struct genl_info *info)
+{
+        struct taskstats *stats;
+        struct sk_buff *rep_skb;
+        size_t size;
+        u32 pid;
+        int rc;
+
+        size = taskstats_packet_size();
 
         rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
         if (rc < 0)
                 return rc;
 
         rc = -EINVAL;
-        if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
-                u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
-                stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
-                if (!stats)
-                        goto err;
-
-                rc = fill_pid(pid, NULL, stats);
-                if (rc < 0)
-                        goto err;
-        } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
-                u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
-                stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
-                if (!stats)
-                        goto err;
-
-                rc = fill_tgid(tgid, NULL, stats);
-                if (rc < 0)
-                        goto err;
-        } else
+        pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
+        stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
+        if (!stats)
                 goto err;
 
+        rc = fill_stats_for_pid(pid, stats);
+        if (rc < 0)
+                goto err;
         return send_reply(rep_skb, info);
 err:
         nlmsg_free(rep_skb);
         return rc;
 }
 
+static int cmd_attr_tgid(struct genl_info *info)
+{
+        struct taskstats *stats;
+        struct sk_buff *rep_skb;
+        size_t size;
+        u32 tgid;
+        int rc;
+
+        size = taskstats_packet_size();
+
+        rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
+        if (rc < 0)
+                return rc;
+
+        rc = -EINVAL;
+        tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
+        stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
+        if (!stats)
+                goto err;
+
+        rc = fill_stats_for_tgid(tgid, stats);
+        if (rc < 0)
+                goto err;
+        return send_reply(rep_skb, info);
+err:
+        nlmsg_free(rep_skb);
+        return rc;
+}
+
+static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
+{
+        if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
+                return cmd_attr_register_cpumask(info);
+        else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
+                return cmd_attr_deregister_cpumask(info);
+        else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
+                return cmd_attr_pid(info);
+        else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
+                return cmd_attr_tgid(info);
+        else
+                return -EINVAL;
+}
+
 static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
 {
         struct signal_struct *sig = tsk->signal;
@@ -532,8 +602,7 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
         /*
          * Size includes space for nested attributes
          */
-        size = nla_total_size(sizeof(u32)) +
-                nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
+        size = taskstats_packet_size();
 
         is_thread_group = !!taskstats_tgid_alloc(tsk);
         if (is_thread_group) {
@@ -555,9 +624,7 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
         if (!stats)
                 goto err;
 
-        rc = fill_pid(-1, tsk, stats);
-        if (rc < 0)
-                goto err;
+        fill_stats(tsk, stats);
 
         /*
          * Doesn't matter if tsk is the leader or the last group member leaving