X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fptrace.c;h=b14b4a4677296a2e9fc2c4c961b314ffd64e623d;hb=c7b5ebbddf7bcd3651947760f423e3783bbe6573;hp=8b2856aaf6410310d83751e1af1bef61bf447115;hpb=a2c21200f1c81b08cb55e417b68150bba439b646;p=linux-2.6.git

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 8b2856aaf..b14b4a467 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -55,6 +55,15 @@ void __ptrace_unlink(task_t *child)
 	REMOVE_LINKS(child);
 	child->parent = child->real_parent;
 	SET_LINKS(child);
+
+	if (child->state == TASK_TRACED) {
+		/*
+		 * Turn a tracing stop into a normal stop now,
+		 * since with no tracer there would be no way
+		 * to wake it up with SIGCONT or SIGKILL.
+		 */
+		child->state = TASK_STOPPED;
+	}
 }
 
 /*
@@ -62,20 +71,35 @@ void __ptrace_unlink(task_t *child)
  */
 int ptrace_check_attach(struct task_struct *child, int kill)
 {
-	if (!(child->ptrace & PT_PTRACED))
-		return -ESRCH;
+	int ret = -ESRCH;
 
-	if (child->parent != current)
-		return -ESRCH;
+	/*
+	 * We take the read lock around doing both checks to close a
+	 * possible race where someone else was tracing our child and
+	 * detached between these two checks.  After this locked check,
+	 * we are sure that this is our traced child and that can only
+	 * be changed by us so it's not changing right after this.
+	 */
+	read_lock(&tasklist_lock);
+	if ((child->ptrace & PT_PTRACED) && child->parent == current &&
+	    child->signal != NULL) {
+		ret = 0;
+		spin_lock_irq(&child->sighand->siglock);
+		if (child->state == TASK_STOPPED) {
+			child->state = TASK_TRACED;
+		} else if (child->state != TASK_TRACED && !kill) {
+			ret = -ESRCH;
+		}
+		spin_unlock_irq(&child->sighand->siglock);
+	}
+	read_unlock(&tasklist_lock);
 
-	if (!kill) {
-		if (child->state != TASK_STOPPED)
-			return -ESRCH;
+	if (!ret && !kill) {
 		wait_task_inactive(child);
 	}
 
 	/* All systems go.. */
-	return 0;
+	return ret;
 }
 
 int ptrace_attach(struct task_struct *task)
@@ -178,8 +202,6 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
 		if (bytes > PAGE_SIZE-offset)
 			bytes = PAGE_SIZE-offset;
 
-		flush_cache_page(vma, addr);
-
 		maddr = kmap(page);
 		if (write) {
 			copy_to_user_page(vma, page, addr,
@@ -322,24 +344,3 @@ int ptrace_request(struct task_struct *child, long request,
 
 	return ret;
 }
-
-void ptrace_notify(int exit_code)
-{
-	BUG_ON (!(current->ptrace & PT_PTRACED));
-
-	/* Let the debugger run.  */
-	current->exit_code = exit_code;
-	set_current_state(TASK_STOPPED);
-	notify_parent(current, SIGCHLD);
-	schedule();
-
-	/*
-	 * Signals sent while we were stopped might set TIF_SIGPENDING.
-	 */
-
-	spin_lock_irq(&current->sighand->siglock);
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
-}
-
-EXPORT_SYMBOL(ptrace_notify);