4 files changed, 65 insertions, 25 deletions

diff --git a/kernel/extable.c b/kernel/extable.c
index 7501b531cee..7fe26285531 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -40,7 +40,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 	return e;
 }
 
-static int core_kernel_text(unsigned long addr)
+int core_kernel_text(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext &&
 	    addr <= (unsigned long)_etext)
diff --git a/kernel/module.c b/kernel/module.c
index d24deb0dbbc..bbe04862e1b 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -705,14 +705,14 @@ EXPORT_SYMBOL(__symbol_put);
 
 void symbol_put_addr(void *addr)
 {
-	unsigned long flags;
+	struct module *modaddr;
 
-	spin_lock_irqsave(&modlist_lock, flags);
-	if (!kernel_text_address((unsigned long)addr))
-		BUG();
+	if (core_kernel_text((unsigned long)addr))
+		return;
 
-	module_put(module_text_address((unsigned long)addr));
-	spin_unlock_irqrestore(&modlist_lock, flags);
+	if (!(modaddr = module_text_address((unsigned long)addr)))
+		BUG();
+	module_put(modaddr);
 }
 EXPORT_SYMBOL_GPL(symbol_put_addr);
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 4e0f0ec003f..921c22ad16e 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -148,12 +148,34 @@ int ptrace_may_attach(struct task_struct *task)
 int ptrace_attach(struct task_struct *task)
 {
 	int retval;
-	task_lock(task);
+
 	retval = -EPERM;
 	if (task->pid <= 1)
-		goto bad;
+		goto out;
 	if (task->tgid == current->tgid)
-		goto bad;
+		goto out;
+
+repeat:
+	/*
+	 * Nasty, nasty.
+	 *
+	 * We want to hold both the task-lock and the
+	 * tasklist_lock for writing at the same time.
+	 * But that's against the rules (tasklist_lock
+	 * is taken for reading by interrupts on other
+	 * cpu's that may have task_lock).
+	 */
+	task_lock(task);
+	local_irq_disable();
+	if (!write_trylock(&tasklist_lock)) {
+		local_irq_enable();
+		task_unlock(task);
+		do {
+			cpu_relax();
+		} while (!write_can_lock(&tasklist_lock));
+		goto repeat;
+	}
+
 	/* the same process cannot be attached many times */
 	if (task->ptrace & PT_PTRACED)
 		goto bad;
@@ -166,17 +188,15 @@ int ptrace_attach(struct task_struct *task)
 				      ? PT_ATTACHED : 0);
 	if (capable(CAP_SYS_PTRACE))
 		task->ptrace |= PT_PTRACE_CAP;
-	task_unlock(task);
 
-	write_lock_irq(&tasklist_lock);
 	__ptrace_link(task, current);
-	write_unlock_irq(&tasklist_lock);
 
 	force_sig_specific(SIGSTOP, task);
-	return 0;
 
 bad:
+	write_unlock_irq(&tasklist_lock);
 	task_unlock(task);
+out:
 	return retval;
 }
 
@@ -417,21 +437,22 @@ int ptrace_request(struct task_struct *child, long request,
  */
 int ptrace_traceme(void)
 {
-	int ret;
+	int ret = -EPERM;
 
 	/*
 	 * Are we already being traced?
 	 */
-	if (current->ptrace & PT_PTRACED)
-		return -EPERM;
-	ret = security_ptrace(current->parent, current);
-	if (ret)
-		return -EPERM;
-	/*
-	 * Set the ptrace bit in the process ptrace flags.
-	 */
-	current->ptrace |= PT_PTRACED;
-	return 0;
+	task_lock(current);
+	if (!(current->ptrace & PT_PTRACED)) {
+		ret = security_ptrace(current->parent, current);
+		/*
+		 * Set the ptrace bit in the process ptrace flags.
+		 */
+		if (!ret)
+			current->ptrace |= PT_PTRACED;
+	}
+	task_unlock(current);
+	return ret;
 }
 
 /**
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 6d32ff26f94..2058f88c7bb 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -479,12 +479,31 @@ static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
 	return 0;
 }
 
+/*
+ * Check to see if there is any immediate RCU-related work to be done
+ * by the current CPU, returning 1 if so.  This function is part of the
+ * RCU implementation; it is -not- an exported member of the RCU API.
+ */
 int rcu_pending(int cpu)
 {
 	return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) ||
 		__rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
 }
 
+/*
+ * Check to see if any future RCU-related work will need to be done
+ * by the current CPU, even if none need be done immediately, returning
+ * 1 if so.  This function is part of the RCU implementation; it is -not-
+ * an exported member of the RCU API.
+ */
+int rcu_needs_cpu(int cpu)
+{
+	struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
+	struct rcu_data *rdp_bh = &per_cpu(rcu_bh_data, cpu);
+
+	return (!!rdp->curlist || !!rdp_bh->curlist || rcu_pending(cpu));
+}
+
 void rcu_check_callbacks(int cpu, int user)
 {
 	if (user ||