[PATCH 64] convert ptrace_setsiginfo() to use ptrace_rw_siginfo()

[Oleg Nesterov]

Like the previous patch, but if the tracee didn't report a signal we
do nothing but return success.

Currently ptrace_notify() always sets ->last_siginfo != NULL which can
be update via PTRACE_SETSIGINFO, but this info will be never used.
We pretend siginfo was updated for compatibility but the stupid app
can read it back, in this case we will have bug-reports.

---

 kernel/ptrace.c |   28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

--- PU/kernel/ptrace.c~64_PUT_SIGINFO	2009-10-03 03:19:47.000000000 +0200
+++ PU/kernel/ptrace.c	2009-10-03 03:44:56.000000000 +0200
@@ -820,22 +820,18 @@ static int ptrace_getsiginfo(struct ptra
 	return 0;
 }
 
-static int ptrace_setsiginfo(struct utrace_engine *engine,
-				struct task_struct *child, const siginfo_t *info)
+static int ptrace_setsiginfo(struct ptrace_context *context,
+				struct task_struct *tracee, siginfo_t *info)
 {
-	unsigned long flags;
-	int error = -ESRCH;
+	/* jctl stop ? */
+	if (!ev_pending(context))
+		return -EINVAL;
 
-	if (lock_task_sighand(child, &flags)) {
-		error = -EINVAL;
-		if (likely(ptrace_context(engine)->siginfo != NULL)) {
-			*ptrace_context(engine)->siginfo = *info;
-			error = 0;
-		}
-		unlock_task_sighand(child, &flags);
-	}
+	if (context->siginfo)
+		return ptrace_rw_siginfo(tracee, context, info, true);
 
-	return error;
+	/* compatibility: pretend it was updated */
+	return 0;
 }
 
 
@@ -1058,7 +1054,8 @@ int ptrace_request(struct task_struct *c
 				   sizeof siginfo))
 			ret = -EFAULT;
 		else
-			ret = ptrace_setsiginfo(engine, child, &siginfo);
+			ret = ptrace_setsiginfo(ptrace_context(engine),
+						child, &siginfo);
 		break;
 
 	case PTRACE_DETACH:	 /* detach a process that was attached. */
@@ -1230,7 +1227,8 @@ int compat_ptrace_request(struct task_st
 			    &siginfo, (struct compat_siginfo __user *) datap))
 			ret = -EFAULT;
 		else
-			ret = ptrace_setsiginfo(engine, child, &siginfo);
+			ret = ptrace_setsiginfo(ptrace_context(engine),
+						child, &siginfo);
 		break;
 
 	default: