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[RFC][PATCH] Static init struct pid for swapper [message #17141] Sat, 13 January 2007 21:57 Go to next message
Sukadev Bhattiprolu is currently offline  Sukadev Bhattiprolu
Messages: 413
Registered: August 2006
Senior Member
 
From: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Subject: Statically initialize struct pid for swapper

Statically initialize a struct pid for the swapper process (pid_t == 0)
and attach it to init_task. This is needed so task_pid(), task_pgrp()
and task_session() interfaces work on the swapper process also.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: containers@lists.osdl.org

---
 arch/alpha/kernel/init_task.c     |    1 +
 arch/arm/kernel/init_task.c       |    1 +
 arch/arm26/kernel/init_task.c     |    1 +
 arch/avr32/kernel/init_task.c     |    1 +
 arch/frv/kernel/init_task.c       |    1 +
 arch/h8300/kernel/init_task.c     |    1 +
 arch/i386/kernel/init_task.c      |    1 +
 arch/ia64/kernel/init_task.c      |    1 +
 arch/m32r/kernel/init_task.c      |    1 +
 arch/m68knommu/kernel/init_task.c |    1 +
 arch/mips/kernel/init_task.c      |    1 +
 arch/parisc/kernel/init_task.c    |    1 +
 arch/powerpc/kernel/init_task.c   |    1 +
 arch/s390/kernel/init_task.c      |    1 +
 arch/sh/kernel/init_task.c        |    1 +
 arch/sh64/kernel/init_task.c      |    1 +
 arch/sparc/kernel/init_task.c     |    1 +
 arch/sparc64/kernel/init_task.c   |    1 +
 arch/um/kernel/init_task.c        |    1 +
 arch/v850/kernel/init_task.c      |    1 +
 arch/x86_64/kernel/init_task.c    |    1 +
 include/linux/init_task.h         |   33 +++++++++++++++++++++++++++++++++
 22 files changed, 54 insertions(+)

Index: lx26-20-rc2-mm1/arch/x86_64/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/x86_64/kernel/init_task.c	2007-01-13 04:38:35.892740080 -0800
+++ lx26-20-rc2-mm1/arch/x86_64/kernel/init_task.c	2007-01-13 04:57:58.930931400 -0800
@@ -14,6 +14,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/include/linux/init_task.h
===================================================================
--- lx26-20-rc2-mm1.orig/include/linux/init_task.h	2007-01-13 04:38:35.893739928 -0800
+++ lx26-20-rc2-mm1/include/linux/init_task.h	2007-01-13 05:25:52.178559096 -0800
@@ -88,6 +88,19 @@ extern struct nsproxy init_nsproxy;
 
 extern struct group_info init_groups;
 
+#define INIT_STRUCT_PID {						\
+	.count 		= ATOMIC_INIT(1),				\
+	.nr		= 0, 						\
+	/* Do we need to put this struct pid in pid_hash ? */		\
+	.pid_chain	= { .next = NULL, .pprev = NULL },		\
+	.tasks 		=  { 						\
+		{ .first = &init_task.pids[PIDTYPE_PID].node },		\
+		{ .first = &init_task.pids[PIDTYPE_PGID].node },	\
+		{ .first = &init_task.pids[PIDTYPE_SID].node },		\
+	}, 								\
+	.rcu		= RCU_HEAD_INIT, 				\
+}
+
 /*
  *  INIT_TASK is used to set up the first task table, touch at
  * your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -139,6 +152,26 @@ extern struct group_info init_groups;
 	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
 	.fs_excl	= ATOMIC_INIT(0),				\
 	.pi_lock	= SPIN_LOCK_UNLOCKED,				\
+	.pids = {							\
+		{ .node = {						\
+		 	.next = NULL,					\
+		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PID].first,\
+		  },							\
+		  .pid = &init_struct_pid,				\
+		},							\
+		{ .node = {						\
+		 	.next = NULL,					\
+		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PGID].first,\
+		  },							\
+		  .pid = &init_struct_pid,				\
+		},							\
+		{ .node = {						\
+		 	.next = NULL,					\
+		  	.pprev = &init_struct_pid.tasks[PIDTYPE_SID].first,\
+		  },							\
+		  .pid = &init_struct_pid,				\
+		},							\
+	}								\
 	INIT_TRACE_IRQFLAGS						\
 	INIT_LOCKDEP							\
 }
Index: lx26-20-rc2-mm1/arch/alpha/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/alpha/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/alpha/kernel/init_task.c	2007-01-13 12:41:56.745940256 -0800
@@ -12,6 +12,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 struct task_struct init_task = INIT_TASK(init_task);
 
Index: lx26-20-rc2-mm1/arch/arm/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/arm/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/arm/kernel/init_task.c	2007-01-13 12:42:18.614615712 -0800
@@ -16,6 +16,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/arm26/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/arm26/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/arm26/kernel/init_task.c	2007-01-13 12:42:12.116603560 -0800
@@ -19,6 +19,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/avr32/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/avr32/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/avr32/kernel/init_task.c	2007-01-13 12:42:25.664543960 -0800
@@ -17,6 +17,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/frv/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/frv/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/frv/kernel/init_task.c	2007-01-13 12:42:37.605728624 -0800
@@ -14,6 +14,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/h8300/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/h8300/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/h8300/kernel/init_task.c	2007-01-13 12:42:42.575973032 -0800
@@ -16,6 +16,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/i386/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/i386/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/i386/kernel/init_task.c	2007-01-13 12:42:52.308493464 -0800
@@ -14,6 +14,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/ia64/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/ia64/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/ia64/kernel/init_task.c	2007-01-13 12:43:03.647769632 -0800
@@ -20,6 +20,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+static struct pid init_struct_pid = INIT_STRUCT_PID;
 struct mm_struct init_mm = INIT_MM(init_mm);
 
 EXPORT_SYMBOL(init_mm);
Index: lx26-20-rc2-mm1/arch/m32r/kernel/init_task.c
===================================================================
--- lx26-20-rc2-mm1.orig/arch/m32r/kernel/init_task.c	2006-11-29 13:57:37.000000000 -0800
+++ lx26-20-rc2-mm1/arch/m32r/kernel/init_task.c	2007-01-13 12:43:08.006107064 -0800
@@ -15,6 +15,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct in
 ...

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Re: [RFC][PATCH] Static init struct pid for swapper [message #17143 is a reply to message #17141] Mon, 15 January 2007 15:16 Go to previous messageGo to next message
ebiederm is currently offline  ebiederm
Messages: 1354
Registered: February 2006
Senior Member
 
Sukadev Bhattiprolu <sukadev@us.ibm.com> writes:

> From: Sukadev Bhattiprolu <sukadev@us.ibm.com>
> Subject: Statically initialize struct pid for swapper
>
> Statically initialize a struct pid for the swapper process (pid_t == 0)
> and attach it to init_task. This is needed so task_pid(), task_pgrp()
> and task_session() interfaces work on the swapper process also.

This looks encouraging.  

We still need to address the fact that we are placing pid == 1
in an invalid process group and session.  We need to call something
like setsid() to address this before we start any other threads
or /sbin/init.

All of the other idle threads are created with fork_idle() from
pid == 1 in the smp startup code, so there are still some differences
but that is independent of your patch.

Just please pass the pid as a struct pid into copy_process and
then we can remove the if (likely(p->pid)) case and use attach_pid
for everything.  And please call setsid() or the equivalent about
where we recognize we are the child_reaper in init(), before we run
any other threads.

Oh yes.  Please fix your whitespace damage in the initializer.

>  /*
>   *  INIT_TASK is used to set up the first task table, touch at
>   * your own risk!. Base=0, limit=0x1fffff (=2MB)
> @@ -139,6 +152,26 @@ extern struct group_info init_groups;
>  	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
>  	.fs_excl	= ATOMIC_INIT(0),				\
>  	.pi_lock	= SPIN_LOCK_UNLOCKED,				\
> +	.pids = {							\
> +		{ .node = {						\
> +		 	.next = NULL,					\
> +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PID].first,\
> +		  },							\
> +		  .pid = &init_struct_pid,				\
> +		},							\
> +		{ .node = {						\
> +		 	.next = NULL,					\
> +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PGID].first,\
> +		  },							\
> +		  .pid = &init_struct_pid,				\
> +		},							\
> +		{ .node = {						\
> +		 	.next = NULL,					\
> +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_SID].first,\
> +		  },							\
> +		  .pid = &init_struct_pid,				\
> +		},							\
> +	}								\
>  	INIT_TRACE_IRQFLAGS						\
>  	INIT_LOCKDEP							\
>  }

Say something like:

#define INIT_PID_LINK(TYPE) = 					\
{								\
	.node = {						\
		.next = NULL,					\
		.pprev = &init_struct_pid.tasks[TYPE].first,	\
	},							\
	.pid = &init_struct_pid,				\
}

And then:

	.pids = {
		[PIDTYPE_PID]  = INIT_PID_LINK(PIDTYPE_PID),
		[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID),
                [PIDTYPE_SID]  = INIT_PID_LINK(PIDTYPE_SID),
	}

As for the question below.  It would be very bad if pid 0 every gets
into the pid hash table.   We have a number of cases that explicitly

+#define INIT_STRUCT_PID {						\
+	.count 		= ATOMIC_INIT(1),				\
+	.nr		= 0, 						\
+	/* Do we need to put this struct pid in pid_hash ? */		\
+	.pid_chain	= { .next = NULL, .pprev = NULL },		\
+	.tasks 		=  { 						\
+		{ .first = &init_task.pids[PIDTYPE_PID].node },		\
+		{ .first = &init_task.pids[PIDTYPE_PGID].node },	\
+		{ .first = &init_task.pids[PIDTYPE_SID].node },		\
+	}, 								\
+	.rcu		= RCU_HEAD_INIT, 				\
+}
+


And one final thing.  Please place init_pid in pid.c.  We can just put
an "extern struct pid init_pid;" in pid.h 

There is no reason to put a separate copy in every architecture and it
will be easier to have just a single copy in the code.  


Eric

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Re: [RFC][PATCH] Static init struct pid for swapper [message #17144 is a reply to message #17143] Tue, 16 January 2007 03:19 Go to previous message
Sukadev Bhattiprolu is currently offline  Sukadev Bhattiprolu
Messages: 413
Registered: August 2006
Senior Member
 
Eric W. Biederman [ebiederm@xmission.com] wrote:
| Sukadev Bhattiprolu <sukadev@us.ibm.com> writes:
| 
| > From: Sukadev Bhattiprolu <sukadev@us.ibm.com>
| > Subject: Statically initialize struct pid for swapper
| >
| > Statically initialize a struct pid for the swapper process (pid_t == 0)
| > and attach it to init_task. This is needed so task_pid(), task_pgrp()
| > and task_session() interfaces work on the swapper process also.
| 
| This looks encouraging.
| 
| We still need to address the fact that we are placing pid == 1
| in an invalid process group and session.  We need to call something
| like setsid() to address this before we start any other threads
| or /sbin/init.

Maybe I am missing something. INIT_SIGNALS sets pgid = 1, sid = 1 for
the swapper and this is passed on to /sbin/init in copy_process.
i.e after copy_process() the thread that would become /sbin/init has
pgid = sid = 1 - isn't that what we want ?

| All of the other idle threads are created with fork_idle() from
| pid == 1 in the smp startup code, so there are still some differences
| but that is independent of your patch.
| 
| Just please pass the pid as a struct pid into copy_process and
| then we can remove the if (likely(p->pid)) case and use attach_pid
| for everything.

Done. Will send out the patch. I have kept it separate from the static
init patch for now.

| And please call setsid() or the equivalent about
| where we recognize we are the child_reaper in init(), before we run
| any other threads.

I need to understand this better, pls see my question above.

| 
| Oh yes.  Please fix your whitespace damage in the initializer.

I think I fixed it now.

| 
| >  /*
| >   *  INIT_TASK is used to set up the first task table, touch at
| >   * your own risk!. Base=0, limit=0x1fffff (=2MB)
| > @@ -139,6 +152,26 @@ extern struct group_info init_groups;
| >  	.cpu_timers	= INIT_CPU_TIMERS(tsk.cpu_timers),		\
| >  	.fs_excl	= ATOMIC_INIT(0),				\
| >  	.pi_lock	= SPIN_LOCK_UNLOCKED,				\
| > +	.pids = {							\
| > +		{ .node = {						\
| > +		 	.next = NULL,					\
| > +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PID].first,\
| > +		  },							\
| > +		  .pid = &init_struct_pid,				\
| > +		},							\
| > +		{ .node = {						\
| > +		 	.next = NULL,					\
| > +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_PGID].first,\
| > +		  },							\
| > +		  .pid = &init_struct_pid,				\
| > +		},							\
| > +		{ .node = {						\
| > +		 	.next = NULL,					\
| > +		  	.pprev = &init_struct_pid.tasks[PIDTYPE_SID].first,\
| > +		  },							\
| > +		  .pid = &init_struct_pid,				\
| > +		},							\
| > +	}								\
| >  	INIT_TRACE_IRQFLAGS						\
| >  	INIT_LOCKDEP							\
| >  }
| 
| Say something like:
| 
| #define INIT_PID_LINK(TYPE) = 					\
| {								\
| 	.node = {						\
| 		.next = NULL,					\
| 		.pprev = &init_struct_pid.tasks[TYPE].first,	\
| 	},							\
| 	.pid = &init_struct_pid,				\
| }
| 
| And then:
| 
| 	.pids = {
| 		[PIDTYPE_PID]  = INIT_PID_LINK(PIDTYPE_PID),
| 		[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID),
|                 [PIDTYPE_SID]  = INIT_PID_LINK(PIDTYPE_SID),
| 	}

Yes. Good idea.

| 
| As for the question below.  It would be very bad if pid 0 every gets
| into the pid hash table.   We have a number of cases that explicitly
| 

Ok.

| +#define INIT_STRUCT_PID {						\
| +	.count 		= ATOMIC_INIT(1),				\
| +	.nr		= 0, 						\
| +	/* Do we need to put this struct pid in pid_hash ? */		\
| +	.pid_chain	= { .next = NULL, .pprev = NULL },		\
| +	.tasks 		=  { 						\
| +		{ .first = &init_task.pids[PIDTYPE_PID].node },		\
| +		{ .first = &init_task.pids[PIDTYPE_PGID].node },	\
| +		{ .first = &init_task.pids[PIDTYPE_SID].node },		\
| +	}, 								\
| +	.rcu		= RCU_HEAD_INIT, 				\
| +}
| +
| 
| 
| And one final thing.  Please place init_pid in pid.c.  We can just put
| an "extern struct pid init_pid;" in pid.h
| 
| There is no reason to put a separate copy in every architecture and it
| will be easier to have just a single copy in the code.

Good idea. I have updated my patch. I was wondering about it myself.

| 
| 
| Eric
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