[Devel] [PATCH 3/5] Use struct pid parameter in copy_process()

[sukadev at us.ibm.com]

From: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Subject: [PATCH 3/5] Use struct pid parameter in copy_process()

Modify copy_process() to take a struct pid * parameter instead of a pid_t.
This simplifies the code a bit and also avoids having to call find_pid()
to convert the pid_t to a struct pid.

Changelog: 
	- Fixed Badari Pulavarty's comments and passed in &init_struct_pid
	  from fork_idle().
	- Fixed Eric Biederman's comments and simplified this patch and
	  used a new patch to remove the likely(pid) check.

Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Cc: Cedric Le Goater <clg at fr.ibm.com>
Cc: Dave Hansen <haveblue at us.ibm.com>
Cc: Serge Hallyn <serue at us.ibm.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: containers at lists.osdl.org
Acked-by: Eric W. Biederman <ebiederm at xmission.com>
---
 kernel/fork.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Index: lx26-21-rc3-mm2/kernel/fork.c
===================================================================
--- lx26-21-rc3-mm2.orig/kernel/fork.c	2007-03-12 17:16:39.000000000 -0700
+++ lx26-21-rc3-mm2/kernel/fork.c	2007-03-12 17:17:48.000000000 -0700
@@ -966,7 +966,7 @@ static struct task_struct *copy_process(
 					unsigned long stack_size,
 					int __user *parent_tidptr,
 					int __user *child_tidptr,
-					int pid)
+					struct pid *pid)
 {
 	int retval;
 	struct task_struct *p = NULL;
@@ -1033,7 +1033,7 @@ static struct task_struct *copy_process(
 	p->did_exec = 0;
 	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
 	copy_flags(clone_flags, p);
-	p->pid = pid;
+	p->pid = pid_nr(pid);
 
 	INIT_LIST_HEAD(&p->children);
 	INIT_LIST_HEAD(&p->sibling);
@@ -1265,7 +1265,7 @@ static struct task_struct *copy_process(
 			list_add_tail_rcu(&p->tasks, &init_task.tasks);
 			__get_cpu_var(process_counts)++;
 		}
-		attach_pid(p, PIDTYPE_PID, find_pid(p->pid));
+		attach_pid(p, PIDTYPE_PID, pid);
 		nr_threads++;
 	}
 
@@ -1336,7 +1336,8 @@ struct task_struct * __cpuinit fork_idle
 	struct task_struct *task;
 	struct pt_regs regs;
 
-	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
+	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL,
+				&init_struct_pid);
 	if (!IS_ERR(task))
 		init_idle(task, cpu);
 
@@ -1364,7 +1365,7 @@ long do_fork(unsigned long clone_flags,
 		return -EAGAIN;
 	nr = pid->nr;
 
-	p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, nr);
+	p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
 	/*
 	 * Do this prior waking up the new thread - the thread pointer
 	 * might get invalid after that point, if the thread exits quickly.
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