[PATCH] Hotplug CPU prep III: daemonize idle tasks

[PATCH] Hotplug CPU prep III: daemonize idle tasks

[Rusty Russell]

This patch introduces __daemonize(task), so idle tasks can be detached
after cloning (required for late creation of idle tasks).

This is independent of the last two patches.

Name: Daemonize idle task
Author: Rusty Russell

D: This patch allows daemonize() to be called on another process (if
D: not started yet), and calls it on the idle task.

diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.14-dofork+clonepid/include/linux/sched.h tmp/include/linux/sched.h
--- working-2.5.14-dofork+clonepid/include/linux/sched.h	Thu May  9 18:25:21 2002
+++ tmp/include/linux/sched.h	Thu May  9 18:36:17 2002
@@ -654,7 +654,12 @@
 extern void exit_sighand(struct task_struct *);
 
 extern void reparent_to_init(void);
-extern void daemonize(void);
+extern void __daemonize(struct task_struct *);
+static inline void daemonize(void)
+{
+	__daemonize(current);
+}
+
 extern task_t *child_reaper;
 
 extern int do_execve(char *, char **, char **, struct pt_regs *);
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.14-dofork+clonepid/kernel/exit.c tmp/kernel/exit.c
--- working-2.5.14-dofork+clonepid/kernel/exit.c	Mon Apr 29 16:00:29 2002
+++ tmp/kernel/exit.c	Thu May  9 18:36:17 2002
@@ -201,32 +201,30 @@
  *	Put all the gunge required to become a kernel thread without
  *	attached user resources in one place where it belongs.
  */
-
-void daemonize(void)
+void __daemonize(struct task_struct *tsk)
 {
 	struct fs_struct *fs;
 
-
 	/*
 	 * If we were started as result of loading a module, close all of the
 	 * user space pages.  We don't need them, and if we didn't close them
 	 * they would be locked into memory.
 	 */
-	exit_mm(current);
+	exit_mm(tsk);
 
-	current->session = 1;
-	current->pgrp = 1;
-	current->tty = NULL;
+	tsk->session = 1;
+	tsk->pgrp = 1;
+	tsk->tty = NULL;
 
 	/* Become as one with the init task */
 
-	exit_fs(current);	/* current->fs->count--; */
+	exit_fs(tsk);	/* current->fs->count--; */
 	fs = init_task.fs;
-	current->fs = fs;
+	tsk->fs = fs;
 	atomic_inc(&fs->count);
- 	exit_files(current);
-	current->files = init_task.files;
-	atomic_inc(&current->files->count);
+ 	exit_files(tsk);
+	tsk->files = init_task.files;
+	atomic_inc(&tsk->files->count);
 }
 
 /*
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.14-dofork+clonepid/kernel/sched.c tmp/kernel/sched.c
--- working-2.5.14-dofork+clonepid/kernel/sched.c	Wed May  1 15:09:29 2002
+++ tmp/kernel/sched.c	Thu May  9 18:45:17 2002
@@ -1555,6 +1555,8 @@
 	runqueue_t *idle_rq = cpu_rq(cpu), *rq = cpu_rq(idle->thread_info->cpu);
 	unsigned long flags;
 
+	if (idle != &init_task)
+		__daemonize(idle);
 	__save_flags(flags);
 	__cli();
 	double_rq_lock(idle_rq, rq);

--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

RE: [PATCH] Hotplug CPU prep III: daemonize idle tasks

[BALBIR SINGH]

[-- Attachment #1: Type: text/plain, Size: 4071 bytes --]

I tried a version of __daemonize in 2.4. It panics in
schedule()

        prepare_to_switch();
        {
                struct mm_struct *mm = next->mm;
                struct mm_struct *oldmm = prev->active_mm;
                if (!mm) {
                        if (next->active_mm) BUG();

I got hit by the BUG() in 2.4, I think prepare_to_switch has
moved to specific archs in 2.5. A quick look showed that
this issue no longer exists in 2.5.

Comments,
Balbir Singh.

|-----Original Message-----
|From: linux-kernel-owner@vger.kernel.org
|[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Rusty Russell
|Sent: Thursday, May 09, 2002 2:20 PM
|To: torvalds@transmeta.com
|Cc: linux-kernel@vger.kernel.org
|Subject: [PATCH] Hotplug CPU prep III: daemonize idle tasks
|
|
|This patch introduces __daemonize(task), so idle tasks can be detached
|after cloning (required for late creation of idle tasks).
|
|This is independent of the last two patches.
|
|Name: Daemonize idle task
|Author: Rusty Russell
|
|D: This patch allows daemonize() to be called on another process (if
|D: not started yet), and calls it on the idle task.
|
|diff -urN -I \$.*\$ --exclude TAGS -X 
|/home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal 
|working-2.5.14-dofork+clonepid/include/linux/sched.h 
|tmp/include/linux/sched.h
|--- working-2.5.14-dofork+clonepid/include/linux/sched.h	Thu 
|May  9 18:25:21 2002
|+++ tmp/include/linux/sched.h	Thu May  9 18:36:17 2002
|@@ -654,7 +654,12 @@
| extern void exit_sighand(struct task_struct *);
| 
| extern void reparent_to_init(void);
|-extern void daemonize(void);
|+extern void __daemonize(struct task_struct *);
|+static inline void daemonize(void)
|+{
|+	__daemonize(current);
|+}
|+
| extern task_t *child_reaper;
| 
| extern int do_execve(char *, char **, char **, struct pt_regs *);
|diff -urN -I \$.*\$ --exclude TAGS -X 
|/home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal 
|working-2.5.14-dofork+clonepid/kernel/exit.c tmp/kernel/exit.c
|--- working-2.5.14-dofork+clonepid/kernel/exit.c	Mon Apr 29 
|16:00:29 2002
|+++ tmp/kernel/exit.c	Thu May  9 18:36:17 2002
|@@ -201,32 +201,30 @@
|  *	Put all the gunge required to become a kernel thread without
|  *	attached user resources in one place where it belongs.
|  */
|-
|-void daemonize(void)
|+void __daemonize(struct task_struct *tsk)
| {
| 	struct fs_struct *fs;
| 
|-
| 	/*
| 	 * If we were started as result of loading a module, close 
|all of the
| 	 * user space pages.  We don't need them, and if we didn't 
|close them
| 	 * they would be locked into memory.
| 	 */
|-	exit_mm(current);
|+	exit_mm(tsk);
| 
|-	current->session = 1;
|-	current->pgrp = 1;
|-	current->tty = NULL;
|+	tsk->session = 1;
|+	tsk->pgrp = 1;
|+	tsk->tty = NULL;
| 
| 	/* Become as one with the init task */
| 
|-	exit_fs(current);	/* current->fs->count--; */
|+	exit_fs(tsk);	/* current->fs->count--; */
| 	fs = init_task.fs;
|-	current->fs = fs;
|+	tsk->fs = fs;
| 	atomic_inc(&fs->count);
|- 	exit_files(current);
|-	current->files = init_task.files;
|-	atomic_inc(&current->files->count);
|+ 	exit_files(tsk);
|+	tsk->files = init_task.files;
|+	atomic_inc(&tsk->files->count);
| }
| 
| /*
|diff -urN -I \$.*\$ --exclude TAGS -X 
|/home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal 
|working-2.5.14-dofork+clonepid/kernel/sched.c tmp/kernel/sched.c
|--- working-2.5.14-dofork+clonepid/kernel/sched.c	Wed May  1 
|15:09:29 2002
|+++ tmp/kernel/sched.c	Thu May  9 18:45:17 2002
|@@ -1555,6 +1555,8 @@
| 	runqueue_t *idle_rq = cpu_rq(cpu), *rq = 
|cpu_rq(idle->thread_info->cpu);
| 	unsigned long flags;
| 
|+	if (idle != &init_task)
|+		__daemonize(idle);
| 	__save_flags(flags);
| 	__cli();
| 	double_rq_lock(idle_rq, rq);
|
|--
|  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
|-
|To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
|the body of a message to majordomo@vger.kernel.org
|More majordomo info at  http://vger.kernel.org/majordomo-info.html
|Please read the FAQ at  http://www.tux.org/lkml/

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Re: [PATCH] Hotplug CPU prep III: daemonize idle tasks

[Rusty Russell]

In message <AAEGIMDAKGCBHLBAACGBAELNCHAA.balbir.singh@wipro.com> you write:
> I tried a version of __daemonize in 2.4. It panics in
> schedule()
> 
>         prepare_to_switch();
>         {
>                 struct mm_struct *mm = next->mm;
>                 struct mm_struct *oldmm = prev->active_mm;
>                 if (!mm) {
>                         if (next->active_mm) BUG();
> 
> I got hit by the BUG() in 2.4, I think prepare_to_switch has
> moved to specific archs in 2.5. A quick look showed that
> this issue no longer exists in 2.5.

Uhhh... there are many other problems if you are trying to do this on
a "live" process.  idle process creation is a special case because it
has never been run yet.

This is not a generic "daemonize this task" mechanism!
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

RE: [PATCH] Hotplug CPU prep III: daemonize idle tasks

[BALBIR SINGH]

[-- Attachment #1: Type: text/plain, Size: 1617 bytes --]

Should __daemonize() check this? check if in the arguments
tsk == current or tsk == idle_task. This would prevent people
from using __daemonize() for the wrong things.

Balbir

|-----Original Message-----
|From: linux-kernel-owner@vger.kernel.org
|[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Rusty Russell
|Sent: Monday, May 13, 2002 7:31 AM
|To: BALBIR SINGH
|Cc: torvalds@transmeta.com; linux-kernel@vger.kernel.org
|Subject: Re: [PATCH] Hotplug CPU prep III: daemonize idle tasks
|
|
|In message <AAEGIMDAKGCBHLBAACGBAELNCHAA.balbir.singh@wipro.com> you write:
|> I tried a version of __daemonize in 2.4. It panics in
|> schedule()
|>
|>         prepare_to_switch();
|>         {
|>                 struct mm_struct *mm = next->mm;
|>                 struct mm_struct *oldmm = prev->active_mm;
|>                 if (!mm) {
|>                         if (next->active_mm) BUG();
|>
|> I got hit by the BUG() in 2.4, I think prepare_to_switch has
|> moved to specific archs in 2.5. A quick look showed that
|> this issue no longer exists in 2.5.
|
|Uhhh... there are many other problems if you are trying to do this on
|a "live" process.  idle process creation is a special case because it
|has never been run yet.
|
|This is not a generic "daemonize this task" mechanism!
|Rusty.
|--
|  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
|-
|To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
|the body of a message to majordomo@vger.kernel.org
|More majordomo info at  http://vger.kernel.org/majordomo-info.html
|Please read the FAQ at  http://www.tux.org/lkml/


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**************************Disclaimer************************************
      


Information contained in this E-MAIL being proprietary to Wipro Limited
is 'privileged' and 'confidential' and intended for use only by the
individual or entity to which it is addressed. You are notified that any
use, copying or dissemination of the information contained in the E-MAIL
in any manner whatsoever is strictly prohibited.



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