[PATCH] update mq_notify to use a struct pid

Message queues can signal a process waiting for a message.

This patch replaces the pid_t value with a struct pid to avoid pid wrap
around problems.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Acked-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 12 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index d75d0ba83360..c45ae86cec31 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -73,7 +73,7 @@ struct mqueue_inode_info {
         struct mq_attr attr;
 
         struct sigevent notify;
-        pid_t notify_owner;
+        struct pid* notify_owner;
         struct user_struct *user;       /* user who created, for accounting */
         struct sock *notify_sock;
         struct sk_buff *notify_cookie;
@@ -134,7 +134,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
                         info->messages = NULL;
-                        info->notify_owner = 0;
+                        info->notify_owner = NULL;
                         info->qsize = 0;
                         info->user = NULL;      /* set when all is ok */
                         memset(&info->attr, 0, sizeof(info->attr));
@@ -338,7 +338,7 @@ static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
                         (info->notify_owner &&
                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
                                 info->notify.sigev_signo : 0,
-                        info->notify_owner);
+                        pid_nr(info->notify_owner));
         spin_unlock(&info->lock);
         buffer[sizeof(buffer)-1] = '\0';
         slen = strlen(buffer)+1;
@@ -363,7 +363,7 @@ static int mqueue_flush_file(struct file *filp, fl_owner_t id)
         struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
 
         spin_lock(&info->lock);
-        if (current->tgid == info->notify_owner)
+        if (task_tgid(current) == info->notify_owner)
                 remove_notification(info);
 
         spin_unlock(&info->lock);
@@ -518,8 +518,8 @@ static void __do_notify(struct mqueue_inode_info *info)
                         sig_i.si_pid = current->tgid;
                         sig_i.si_uid = current->uid;
 
-                        kill_proc_info(info->notify.sigev_signo,
-                                       &sig_i, info->notify_owner);
+                        kill_pid_info(info->notify.sigev_signo,
+                                      &sig_i, info->notify_owner);
                         break;
                 case SIGEV_THREAD:
                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
@@ -528,7 +528,8 @@ static void __do_notify(struct mqueue_inode_info *info)
                         break;
                 }
                 /* after notification unregisters process */
-                info->notify_owner = 0;
+                put_pid(info->notify_owner);
+                info->notify_owner = NULL;
         }
         wake_up(&info->wait_q);
 }
@@ -566,12 +567,13 @@ static long prepare_timeout(const struct timespec __user *u_arg)
 
 static void remove_notification(struct mqueue_inode_info *info)
 {
-        if (info->notify_owner != 0 &&
+        if (info->notify_owner != NULL &&
             info->notify.sigev_notify == SIGEV_THREAD) {
                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
         }
-        info->notify_owner = 0;
+        put_pid(info->notify_owner);
+        info->notify_owner = NULL;
 }
 
 static int mq_attr_ok(struct mq_attr *attr)
@@ -1062,11 +1064,11 @@ retry:
         ret = 0;
         spin_lock(&info->lock);
         if (u_notification == NULL) {
-                if (info->notify_owner == current->tgid) {
+                if (info->notify_owner == task_tgid(current)) {
                         remove_notification(info);
                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
                 }
-        } else if (info->notify_owner != 0) {
+        } else if (info->notify_owner != NULL) {
                 ret = -EBUSY;
         } else {
                 switch (notification.sigev_notify) {
@@ -1086,7 +1088,8 @@ retry:
                         info->notify.sigev_notify = SIGEV_SIGNAL;
                         break;
                 }
-                info->notify_owner = current->tgid;
+
+                info->notify_owner = get_pid(task_tgid(current));
                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
         }
         spin_unlock(&info->lock);