[RFC PATCH 11/12 v2] ptrace: mv task_struct->ptrace_message ptrace_ctx->message

[Oleg Nesterov <oleg@redhat.com>]

Move task_struct->ptrace_message into ptrace_ctx->message.

ptrace_event() can use current->ptrace_ctx safely. If mask == 0 and we do
not check task_ptrace() we are called from tracehook_report_clone_complete(),
in this case trace == T means current was traced when it called do_fork().

 include/linux/sched.h  |    1 -
 include/linux/ptrace.h |    3 ++-
 kernel/ptrace.c        |    6 ++++--
 3 files changed, 6 insertions(+), 4 deletions(-)

--- PTRACE/include/linux/sched.h~10_MESSAGE	2009-05-28 10:45:59.000000000 +0200
+++ PTRACE/include/linux/sched.h	2009-05-28 12:03:26.000000000 +0200
@@ -1347,7 +1347,6 @@ struct task_struct {
 
 	struct io_context *io_context;
 
-	unsigned long ptrace_message;
 	struct task_io_accounting ioac;
 #if defined(CONFIG_TASK_XACCT)
 	u64 acct_rss_mem1;	/* accumulated rss usage */
--- PTRACE/include/linux/ptrace.h~10_MESSAGE	2009-05-28 11:59:06.000000000 +0200
+++ PTRACE/include/linux/ptrace.h	2009-05-28 12:09:30.000000000 +0200
@@ -79,6 +79,7 @@ struct ptrace_context {
 	unsigned long		flags;
 	struct task_struct	*tracer;
 	struct siginfo		*infop;
+	unsigned long		message;
 };
 
 extern int alloc_ptrace_context(struct task_struct *child);
@@ -159,7 +160,7 @@ static inline int ptrace_event(int mask,
 {
 	if (mask && likely(!(task_ptrace(current) & mask)))
 		return 0;
-	current->ptrace_message = message;
+	current->ptrace_ctx->message = message;
 	ptrace_notify((event << 8) | SIGTRAP);
 	return 1;
 }
--- PTRACE/kernel/ptrace.c~10_MESSAGE	2009-05-28 11:29:45.000000000 +0200
+++ PTRACE/kernel/ptrace.c	2009-05-28 12:11:20.000000000 +0200
@@ -568,7 +568,8 @@ int ptrace_request(struct task_struct *c
 		ret = ptrace_setoptions(child->ptrace_ctx, data);
 		break;
 	case PTRACE_GETEVENTMSG:
-		ret = put_user(child->ptrace_message, (unsigned long __user *) data);
+		ret = put_user(child->ptrace_ctx->message,
+				(unsigned long __user *) data);
 		break;
 
 	case PTRACE_GETSIGINFO:
@@ -728,7 +729,8 @@ int compat_ptrace_request(struct task_st
 		break;
 
 	case PTRACE_GETEVENTMSG:
-		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
+		ret = put_user((compat_ulong_t) child->ptrace_ctx->message,
+				datap);
 		break;
 
 	case PTRACE_GETSIGINFO: