[PATCH] knfsd: svcrpc: WARN() instead of returning an error from svc_take_page

[sfrench/cifs-2.6.git] / kernel / ptrace.c

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 17ee7e5a34516f7485250b7a7ef94546907f9b39..0eeb7e66722c899fa2f53ee7b451d981aa91f6a3 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -7,6 +7,7 @@
  * to continually duplicate across every architecture.
  */
 
+#include <linux/capability.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/errno.h>
@@ -29,14 +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);
 }
  
 /*
@@ -71,14 +71,14 @@ 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);
@@ -183,22 +183,27 @@ bad:
        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;
@@ -407,54 +412,62 @@ int ptrace_request(struct task_struct *child, long request,
        return ret;
 }
 
-#ifndef __ARCH_SYS_PTRACE
-static int ptrace_get_task_struct(long request, long pid,
-               struct task_struct **childp)
+/**
+ * ptrace_traceme  --  helper for PTRACE_TRACEME
+ *
+ * Performs checks and sets PT_PTRACED.
+ * Should be used by all ptrace implementations for PTRACE_TRACEME.
+ */
+int ptrace_traceme(void)
 {
-       struct task_struct *child;
        int ret;
 
        /*
-        * Callers use child == NULL as an indication to exit early even
-        * when the return value is 0, so make sure it is non-NULL here.
+        * Are we already being traced?
         */
-       *childp = NULL;
+       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;
+}
 
-       if (request == PTRACE_TRACEME) {
-               /*
-                * 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;
-       }
+/**
+ * ptrace_get_task_struct  --  grab a task struct reference for ptrace
+ * @pid:       process id to grab a task_struct reference of
+ *
+ * This function is a helper for ptrace implementations.  It checks
+ * permissions and then grabs a task struct for use of the actual
+ * ptrace implementation.
+ *
+ * Returns the task_struct for @pid or an ERR_PTR() on failure.
+ */
+struct task_struct *ptrace_get_task_struct(pid_t pid)
+{
+       struct task_struct *child;
 
        /*
-        * You may not mess with init
+        * Tracing init is not allowed.
         */
        if (pid == 1)
-               return -EPERM;
+               return ERR_PTR(-EPERM);
 
-       ret = -ESRCH;
        read_lock(&tasklist_lock);
        child = find_task_by_pid(pid);
        if (child)
                get_task_struct(child);
        read_unlock(&tasklist_lock);
        if (!child)
-               return -ESRCH;
-
-       *childp = child;
-       return 0;
+               return ERR_PTR(-ESRCH);
+       return child;
 }
 
+#ifndef __ARCH_SYS_PTRACE
 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 {
        struct task_struct *child;
@@ -464,9 +477,16 @@ asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
         * This lock_kernel fixes a subtle race with suid exec
         */
        lock_kernel();
-       ret = ptrace_get_task_struct(request, pid, &child);
-       if (!child)
+       if (request == PTRACE_TRACEME) {
+               ret = ptrace_traceme();
                goto out;
+       }
+
+       child = ptrace_get_task_struct(pid);
+       if (IS_ERR(child)) {
+               ret = PTR_ERR(child);
+               goto out;
+       }
 
        if (request == PTRACE_ATTACH) {
                ret = ptrace_attach(child);