From b50e205a613e812da5aa47ff0c6cddde49bcd9fb Mon Sep 17 00:00:00 2001
From: Masamichi Takagi <masamichi.takagi@riken.jp>
Date: Mon, 8 Sep 2014 22:40:56 +0900
Subject: [PATCH] Support pid of zero when calling waitpid

Make waitpid wait any process with the same pgid of the caller when
setting zero to the pid argument.
---
 arch/x86/kernel/syscall.c | 5 +++++
 kernel/include/process.h  | 1 +
 kernel/syscall.c          | 4 +++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/syscall.c b/arch/x86/kernel/syscall.c
index 281620c6..b9b85d5e 100644
--- a/arch/x86/kernel/syscall.c
+++ b/arch/x86/kernel/syscall.c
@@ -183,6 +183,11 @@ do_setpgid(int pid, int pgid)
 				continue;
 			if(p->pid == pid){
 				p->pgid = pgid;
+
+                /* Update pgid in fork_tree because it's used in wait4 */
+                ihk_mc_spinlock_lock_noirq(&p->ftn->lock);
+                p->ftn->pgid = pgid;
+                ihk_mc_spinlock_unlock_noirq(&p->ftn->lock);
 			}
 		}
 		ihk_mc_spinlock_unlock(&(v->runq_lock), irqstate);
diff --git a/kernel/include/process.h b/kernel/include/process.h
index da029f9b..04fbf8c8 100644
--- a/kernel/include/process.h
+++ b/kernel/include/process.h
@@ -144,6 +144,7 @@ struct fork_tree_node {
 
 	struct process *owner;
 	int pid;
+	int pgid;
 	
 	struct fork_tree_node *parent;
 	struct list_head children;
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 6b5db85b..fd5f66f1 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -305,6 +305,7 @@ SYSCALL_DECLARE(wait4)
 	struct process *proc = cpu_local_var(current);
 	struct fork_tree_node *child, *child_iter;
 	int pid = (int)ihk_mc_syscall_arg0(ctx);
+	int pgid = proc->pgid;
 	int *status = (int *)ihk_mc_syscall_arg1(ctx);
 	int options = (int)ihk_mc_syscall_arg2(ctx);
 	int ret;
@@ -326,7 +327,7 @@ rescan:
 
 		ihk_mc_spinlock_lock_noirq(&child_iter->lock);
 		
-		if (pid == -1 || pid == child_iter->pid) {
+		if (pid == -1 || (pid == 0 && pgid == child_iter->pgid) || pid == child_iter->pid) {
 			child = child_iter;
 			break;
 		}
@@ -1395,6 +1396,7 @@ unsigned long do_fork(int clone_flags, unsigned long newsp,
 	}
 
 	new->ftn->pid = new->pid;
+	new->ftn->pgid = new->pgid;
 	
 	if (clone_flags & CLONE_PARENT_SETTID) {
 		dkprintf("clone_flags & CLONE_PARENT_SETTID: 0x%lX\n",