From 8402f058ad4e5ae6176dd7e8c87d3700fa3f1653 Mon Sep 17 00:00:00 2001
From: Hans Petter Selasky <hselasky@FreeBSD.org>
Date: Thu, 6 Apr 2017 10:26:03 +0000
Subject: [PATCH] Fix implementation of task_pid_group_leader() in the
 LinuxKPI.

In FreeBSD thread IDs and procedure IDs have distinct number
spaces. When asking for the group leader task ID in the LinuxKPI,
return the procedure ID and let this resolve to the first task in the
procedure having a valid LinuxKPI task structure pointer.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
---
 .../linuxkpi/common/include/linux/sched.h     |  3 +-
 .../linuxkpi/common/src/linux_current.c       | 31 +++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/sys/compat/linuxkpi/common/include/linux/sched.h b/sys/compat/linuxkpi/common/include/linux/sched.h
index 4439fc00c092..677e18e3ff5d 100644
--- a/sys/compat/linuxkpi/common/include/linux/sched.h
+++ b/sys/compat/linuxkpi/common/include/linux/sched.h
@@ -74,8 +74,7 @@ struct task_struct {
 
 #define	current		((struct task_struct *)curthread->td_lkpi_task)
 
-#define	task_pid_group_leader(task) \
-	FIRST_THREAD_IN_PROC((task)->task_thread->td_proc)->td_tid
+#define	task_pid_group_leader(task) (task)->task_thread->td_proc->p_pid
 #define	task_pid(task)		((task)->pid)
 #define	task_pid_nr(task)	((task)->pid)
 #define	get_pid(x)		(x)
diff --git a/sys/compat/linuxkpi/common/src/linux_current.c b/sys/compat/linuxkpi/common/src/linux_current.c
index fb33aed92846..ca0fb0c4f327 100644
--- a/sys/compat/linuxkpi/common/src/linux_current.c
+++ b/sys/compat/linuxkpi/common/src/linux_current.c
@@ -158,13 +158,28 @@ struct task_struct *
 linux_pid_task(pid_t pid)
 {
 	struct thread *td;
+	struct proc *p;
 
+	/* try to find corresponding thread */
 	td = tdfind(pid, -1);
 	if (td != NULL) {
 		struct task_struct *ts = td->td_lkpi_task;
 		PROC_UNLOCK(td->td_proc);
 		return (ts);
 	}
+
+	/* try to find corresponding procedure */
+	p = pfind(pid);
+	if (p != NULL) {
+		FOREACH_THREAD_IN_PROC(p, td) {
+			struct task_struct *ts = td->td_lkpi_task;
+			if (ts != NULL) {
+				PROC_UNLOCK(p);
+				return (ts);
+			}
+		}
+		PROC_UNLOCK(p);
+	}
 	return (NULL);
 }
 
@@ -172,7 +187,9 @@ struct task_struct *
 linux_get_pid_task(pid_t pid)
 {
 	struct thread *td;
+	struct proc *p;
 
+	/* try to find corresponding thread */
 	td = tdfind(pid, -1);
 	if (td != NULL) {
 		struct task_struct *ts = td->td_lkpi_task;
@@ -181,6 +198,20 @@ linux_get_pid_task(pid_t pid)
 		PROC_UNLOCK(td->td_proc);
 		return (ts);
 	}
+
+	/* try to find corresponding procedure */
+	p = pfind(pid);
+	if (p != NULL) {
+		FOREACH_THREAD_IN_PROC(p, td) {
+			struct task_struct *ts = td->td_lkpi_task;
+			if (ts != NULL) {
+				get_task_struct(ts);
+				PROC_UNLOCK(p);
+				return (ts);
+			}
+		}
+		PROC_UNLOCK(p);
+	}
 	return (NULL);
 }