[PATCH] I2O: Bugfixes to get I2O working again

[pandora-kernel.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 5f33cdb..921c22a 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -30,14 +30,13 @@
  */
 void __ptrace_link(task_t *child, task_t *new_parent)
 {
-       if (!list_empty(&child->ptrace_list))
-               BUG();
+       BUG_ON(!list_empty(&child->ptrace_list));
        if (child->parent == new_parent)
                return;
        list_add(&child->ptrace_list, &child->parent->ptrace_children);
-       REMOVE_LINKS(child);
+       remove_parent(child);
        child->parent = new_parent;
-       SET_LINKS(child);
+       add_parent(child);
 }
  
 /*
@@ -57,10 +56,6 @@ void ptrace_untrace(task_t *child)
                        signal_wake_up(child, 1);
                }
        }
-       if (child->signal->flags & SIGNAL_GROUP_EXIT) {
-               sigaddset(&child->pending.signal, SIGKILL);
-               signal_wake_up(child, 1);
-       }
        spin_unlock(&child->sighand->siglock);
 }
 
@@ -72,17 +67,18 @@ void ptrace_untrace(task_t *child)
  */
 void __ptrace_unlink(task_t *child)
 {
-       if (!child->ptrace)
-               BUG();
+       BUG_ON(!child->ptrace);
+
        child->ptrace = 0;
        if (!list_empty(&child->ptrace_list)) {
                list_del_init(&child->ptrace_list);
-               REMOVE_LINKS(child);
+               remove_parent(child);
                child->parent = child->real_parent;
-               SET_LINKS(child);
+               add_parent(child);
        }
 
-       ptrace_untrace(child);
+       if (child->state == TASK_TRACED)
+               ptrace_untrace(child);
 }
 
 /*
@@ -152,12 +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;
@@ -170,36 +188,39 @@ 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;
 }
 
+void __ptrace_detach(struct task_struct *child, unsigned int data)
+{
+       child->exit_code = data;
+       /* .. re-parent .. */
+       __ptrace_unlink(child);
+       /* .. and wake it up. */
+       if (child->exit_state != EXIT_ZOMBIE)
+               wake_up_process(child);
+}
+
 int ptrace_detach(struct task_struct *child, unsigned int data)
 {
        if (!valid_signal(data))
-               return  -EIO;
+               return -EIO;
 
        /* Architecture-specific hardware disable .. */
        ptrace_disable(child);
 
-       /* .. re-parent .. */
-       child->exit_code = data;
-
        write_lock_irq(&tasklist_lock);
-       __ptrace_unlink(child);
-       /* .. and wake it up. */
-       if (child->exit_state != EXIT_ZOMBIE)
-               wake_up_process(child);
+       if (child->ptrace)
+               __ptrace_detach(child, data);
        write_unlock_irq(&tasklist_lock);
 
        return 0;
@@ -242,8 +263,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
                if (write) {
                        copy_to_user_page(vma, page, addr,
                                          maddr + offset, buf, bytes);
-                       if (!PageCompound(page))
-                               set_page_dirty_lock(page);
+                       set_page_dirty_lock(page);
                } else {
                        copy_from_user_page(vma, page, addr,
                                            buf, maddr + offset, bytes);
@@ -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;
 }
 
 /**