X-Git-Url: http://pilppa.org/gitweb/?a=blobdiff_plain;f=kernel%2Fsys.c;h=e1024383314de0428e4739e0f9c782330ecd63d5;hb=958b7f37ee0fb2846c8d44310a68ae9605614ff9;hp=a0c1a29a507fccc234d699093a84983f77a963fd;hpb=21b4e736922f546e0f1aa7b9d6c442f309a2444a;p=linux-2.6-omap-h63xx.git

diff --git a/kernel/sys.c b/kernel/sys.c
index a0c1a29a507..e1024383314 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -215,7 +215,7 @@ EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
  *	This routine uses RCU to synchronize with changes to the chain.
  *
  *	If the return value of the notifier can be and'ed
- *	with %NOTIFY_STOP_MASK then atomic_notifier_call_chain
+ *	with %NOTIFY_STOP_MASK then atomic_notifier_call_chain()
  *	will return immediately, with the return value of
  *	the notifier function which halted execution.
  *	Otherwise the return value is the return value
@@ -313,7 +313,7 @@ EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
  *	run in a process context, so they are allowed to block.
  *
  *	If the return value of the notifier can be and'ed
- *	with %NOTIFY_STOP_MASK then blocking_notifier_call_chain
+ *	with %NOTIFY_STOP_MASK then blocking_notifier_call_chain()
  *	will return immediately, with the return value of
  *	the notifier function which halted execution.
  *	Otherwise the return value is the return value
@@ -323,11 +323,18 @@ EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
 int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
 		unsigned long val, void *v)
 {
-	int ret;
+	int ret = NOTIFY_DONE;
 
-	down_read(&nh->rwsem);
-	ret = notifier_call_chain(&nh->head, val, v);
-	up_read(&nh->rwsem);
+	/*
+	 * We check the head outside the lock, but if this access is
+	 * racy then it does not matter what the result of the test
+	 * is, we re-check the list after having taken the lock anyway:
+	 */
+	if (rcu_dereference(nh->head)) {
+		down_read(&nh->rwsem);
+		ret = notifier_call_chain(&nh->head, val, v);
+		up_read(&nh->rwsem);
+	}
 	return ret;
 }
 
@@ -386,7 +393,7 @@ EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
  *	All locking must be provided by the caller.
  *
  *	If the return value of the notifier can be and'ed
- *	with %NOTIFY_STOP_MASK then raw_notifier_call_chain
+ *	with %NOTIFY_STOP_MASK then raw_notifier_call_chain()
  *	will return immediately, with the return value of
  *	the notifier function which halted execution.
  *	Otherwise the return value is the return value
@@ -480,7 +487,7 @@ EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);
  *	run in a process context, so they are allowed to block.
  *
  *	If the return value of the notifier can be and'ed
- *	with %NOTIFY_STOP_MASK then srcu_notifier_call_chain
+ *	with %NOTIFY_STOP_MASK then srcu_notifier_call_chain()
  *	will return immediately, with the return value of
  *	the notifier function which halted execution.
  *	Otherwise the return value is the return value
@@ -531,7 +538,7 @@ EXPORT_SYMBOL_GPL(srcu_init_notifier_head);
  *	Registers a function with the list of functions
  *	to be called at reboot time.
  *
- *	Currently always returns zero, as blocking_notifier_chain_register
+ *	Currently always returns zero, as blocking_notifier_chain_register()
  *	always returns zero.
  */
  
@@ -1381,7 +1388,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 
 	if (p->real_parent == group_leader) {
 		err = -EPERM;
-		if (p->signal->session != group_leader->signal->session)
+		if (process_session(p) != process_session(group_leader))
 			goto out;
 		err = -EACCES;
 		if (p->did_exec)
@@ -1397,16 +1404,13 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 		goto out;
 
 	if (pgid != pid) {
-		struct task_struct *p;
+		struct task_struct *g =
+			find_task_by_pid_type(PIDTYPE_PGID, pgid);
 
-		do_each_task_pid(pgid, PIDTYPE_PGID, p) {
-			if (p->signal->session == group_leader->signal->session)
-				goto ok_pgid;
-		} while_each_task_pid(pgid, PIDTYPE_PGID, p);
-		goto out;
+		if (!g || process_session(g) != process_session(group_leader))
+			goto out;
 	}
 
-ok_pgid:
 	err = security_task_setpgid(p, pgid);
 	if (err)
 		goto out;
@@ -1459,7 +1463,7 @@ asmlinkage long sys_getpgrp(void)
 asmlinkage long sys_getsid(pid_t pid)
 {
 	if (!pid)
-		return current->signal->session;
+		return process_session(current);
 	else {
 		int retval;
 		struct task_struct *p;
@@ -1471,7 +1475,7 @@ asmlinkage long sys_getsid(pid_t pid)
 		if (p) {
 			retval = security_task_getsid(p);
 			if (!retval)
-				retval = p->signal->session;
+				retval = process_session(p);
 		}
 		read_unlock(&tasklist_lock);
 		return retval;
@@ -1484,7 +1488,6 @@ asmlinkage long sys_setsid(void)
 	pid_t session;
 	int err = -EPERM;
 
-	mutex_lock(&tty_mutex);
 	write_lock_irq(&tasklist_lock);
 
 	/* Fail if I am already a session leader */
@@ -1504,12 +1507,15 @@ asmlinkage long sys_setsid(void)
 
 	group_leader->signal->leader = 1;
 	__set_special_pids(session, session);
+
+	spin_lock(&group_leader->sighand->siglock);
 	group_leader->signal->tty = NULL;
 	group_leader->signal->tty_old_pgrp = 0;
+	spin_unlock(&group_leader->sighand->siglock);
+
 	err = process_group(group_leader);
 out:
 	write_unlock_irq(&tasklist_lock);
-	mutex_unlock(&tty_mutex);
 	return err;
 }