4 files changed, 65 insertions, 25 deletions

diff --git a/kernel/extable.c b/kernel/extable.c
index 7501b531ceed..7fe262855317 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 d24deb0dbbc9..bbe04862e1b0 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 4e0f0ec003f7..921c22ad16e4 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 6d32ff26f948..2058f88c7bbb 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 ||