[uml-devel] [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[uml-devel] [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[blaisorblade]

From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>, Chris Wedgwood <cw@f00f.org>
CC: Ingo Molnar <mingo@redhat.com>

Currently UML must explicitly call the UML-specific free_irq_by_irq_and_dev()
for each free_irq call it's done.

This is needed because ->shutdown and/or ->disable are only called when the
last "action" for that irq is removed.

Instead, for UML shared IRQs (UML IRQs are very often, if not always, shared),
for each dev_id some setup is done, which must be cleared on the release of
that fd. For instance, for each open console a new instance (i.e. new dev_id)
of the same IRQ is requested().

Exactly, a fd is stored in an array (pollfds), which is after read by a host
thread and passed to poll(). Each event registered by poll() triggers an
interrupt. So, for each free_irq() we must remove the corresponding host fd
from the table, which we do via this -release() method.

In this patch we add an appropriate hook for this, and remove all uses of it
by pointing the hook to the said procedure; this is safe to do since the said
procedure.

Also some cosmetic improvements are included.

This is heavily based on some work by Chris Wedgwood, which however didn't get
the patch merged for something I'd call a "misunderstanding" (the need for
this patch wasn't cleanly explained, thus adding the generic hook was felt as
undesirable).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
---

 linux-2.6.git-paolo/arch/um/drivers/line.c       |    2 --
 linux-2.6.git-paolo/arch/um/drivers/net_kern.c   |    1 -
 linux-2.6.git-paolo/arch/um/drivers/port_kern.c  |    1 -
 linux-2.6.git-paolo/arch/um/drivers/xterm_kern.c |    1 -
 linux-2.6.git-paolo/arch/um/kernel/irq.c         |   11 +++++++----
 linux-2.6.git-paolo/arch/um/kernel/irq_user.c    |    2 --
 linux-2.6.git-paolo/include/linux/irq.h          |    1 +
 linux-2.6.git-paolo/kernel/irq/manage.c          |    4 ++++
 8 files changed, 12 insertions(+), 11 deletions(-)

diff -puN kernel/irq/manage.c~uml-gen-irq-release kernel/irq/manage.c
--- linux-2.6.git/kernel/irq/manage.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/kernel/irq/manage.c	2005-05-25 01:15:46.000000000 +0200
@@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *de
 
 			/* Found it - now remove it from the list of entries */
 			*pp = action->next;
+
+			if (desc->handler->release)
+				desc->handler->release(irq, dev_id);
+
 			if (!desc->action) {
 				desc->status |= IRQ_DISABLED;
 				if (desc->handler->shutdown)
diff -puN include/linux/irq.h~uml-gen-irq-release include/linux/irq.h
--- linux-2.6.git/include/linux/irq.h~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/include/linux/irq.h	2005-05-25 01:15:46.000000000 +0200
@@ -47,6 +47,7 @@ struct hw_interrupt_type {
 	void (*ack)(unsigned int irq);
 	void (*end)(unsigned int irq);
 	void (*set_affinity)(unsigned int irq, cpumask_t dest);
+	void (*release)(unsigned int irq, void *dev_id);
 };
 
 typedef struct hw_interrupt_type  hw_irq_controller;
diff -puN arch/um/kernel/irq_user.c~uml-gen-irq-release arch/um/kernel/irq_user.c
--- linux-2.6.git/arch/um/kernel/irq_user.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/kernel/irq_user.c	2005-05-25 01:15:46.000000000 +0200
@@ -85,8 +85,6 @@ void sigio_handler(int sig, union uml_pt
 				next = irq_fd->next;
 				if(irq_fd->freed){
 					free_irq(irq_fd->irq, irq_fd->id);
-					free_irq_by_irq_and_dev(irq_fd->irq,
-								irq_fd->id);
 				}
 			}
 		}
diff -puN arch/um/drivers/net_kern.c~uml-gen-irq-release arch/um/drivers/net_kern.c
--- linux-2.6.git/arch/um/drivers/net_kern.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/drivers/net_kern.c	2005-05-25 01:15:46.000000000 +0200
@@ -146,7 +146,6 @@ static int uml_net_close(struct net_devi
 	netif_stop_queue(dev);
 	spin_lock(&lp->lock);
 
-	free_irq_by_irq_and_dev(dev->irq, dev);
 	free_irq(dev->irq, dev);
 	if(lp->close != NULL)
 		(*lp->close)(lp->fd, &lp->user);
diff -puN arch/um/drivers/xterm_kern.c~uml-gen-irq-release arch/um/drivers/xterm_kern.c
--- linux-2.6.git/arch/um/drivers/xterm_kern.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/drivers/xterm_kern.c	2005-05-25 01:15:46.000000000 +0200
@@ -69,7 +69,6 @@ int xterm_fd(int socket, int *pid_out)
 	 * isn't set) this will hang... */
 	wait_for_completion(&data->ready);
 
-	free_irq_by_irq_and_dev(XTERM_IRQ, data);
 	free_irq(XTERM_IRQ, data);
 
 	ret = data->new_fd;
diff -puN arch/um/drivers/port_kern.c~uml-gen-irq-release arch/um/drivers/port_kern.c
--- linux-2.6.git/arch/um/drivers/port_kern.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/drivers/port_kern.c	2005-05-25 01:15:46.000000000 +0200
@@ -257,7 +257,6 @@ int port_wait(void *data)
 		 * connection.  Then we loop here throwing out failed 
 		 * connections until a good one is found.
 		 */
-		free_irq_by_irq_and_dev(TELNETD_IRQ, conn);
 		free_irq(TELNETD_IRQ, conn);
 
 		if(conn->fd >= 0) break;
diff -puN arch/um/drivers/line.c~uml-gen-irq-release arch/um/drivers/line.c
--- linux-2.6.git/arch/um/drivers/line.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/drivers/line.c	2005-05-25 01:15:46.000000000 +0200
@@ -406,14 +406,12 @@ void line_disable(struct tty_struct *tty
 	if(line->driver->read_irq == current_irq)
 		free_irq_later(line->driver->read_irq, tty);
 	else {
-		free_irq_by_irq_and_dev(line->driver->read_irq, tty);
 		free_irq(line->driver->read_irq, tty);
 	}
 
 	if(line->driver->write_irq == current_irq)
 		free_irq_later(line->driver->write_irq, tty);
 	else {
-		free_irq_by_irq_and_dev(line->driver->write_irq, tty);
 		free_irq(line->driver->write_irq, tty);
 	}
 
diff -puN arch/um/include/irq_user.h~uml-gen-irq-release arch/um/include/irq_user.h
diff -puN arch/um/kernel/irq.c~uml-gen-irq-release arch/um/kernel/irq.c
--- linux-2.6.git/arch/um/kernel/irq.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/kernel/irq.c	2005-05-25 01:15:46.000000000 +0200
@@ -124,14 +124,16 @@ void irq_unlock(unsigned long flags)
 	spin_unlock_irqrestore(&irq_spinlock, flags);
 }
 
-/*  presently hw_interrupt_type must define (startup || enable) &&
- *  disable && end */
+/* hw_interrupt_type must define (startup || enable) &&
+ * (shutdown || disable) && end */
 static void dummy(unsigned int irq)
 {
 }
 
-static struct hw_interrupt_type SIGIO_irq_type = {
+/* This is used for everything else than the timer. */
+static struct hw_interrupt_type normal_irq_type = {
 	.typename = "SIGIO",
+	.release = free_irq_by_irq_and_dev,
 	.disable = dummy,
 	.enable = dummy,
 	.ack = dummy,
@@ -140,6 +142,7 @@ static struct hw_interrupt_type SIGIO_ir
 
 static struct hw_interrupt_type SIGVTALRM_irq_type = {
 	.typename = "SIGVTALRM",
+	.release = free_irq_by_irq_and_dev,
 	.shutdown = dummy, /* never called */
 	.disable = dummy,
 	.enable = dummy,
@@ -160,7 +163,7 @@ void __init init_IRQ(void)
 		irq_desc[i].status = IRQ_DISABLED;
 		irq_desc[i].action = NULL;
 		irq_desc[i].depth = 1;
-		irq_desc[i].handler = &SIGIO_irq_type;
+		irq_desc[i].handler = &normal_irq_type;
 		enable_irq(i);
 	}
 }
_


-------------------------------------------------------
This SF.Net email is sponsored by Yahoo.
Introducing Yahoo! Search Developer Network - Create apps using Yahoo!
Search APIs Find out how you can build Yahoo! directly into your own
Applications - visit http://developer.yahoo.net/?fr=offad-ysdn-ostg-q22005
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

[uml-devel] Re: [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[Chris Wedgwood]

On Fri, May 27, 2005 at 02:39:26AM +0200, blaisorblade@yahoo.it wrote:

> From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>, Chris Wedgwood <cw@f00f.org>
> CC: Ingo Molnar <mingo@redhat.com>

[...]

> This is heavily based on some work by Chris Wedgwood, which however
> didn't get the patch merged for something I'd call a
> "misunderstanding" (the need for this patch wasn't cleanly
> explained, thus adding the generic hook was felt as undesirable).

Looks very reasonable to me and your explaination is much better than
mine was :-)

> diff -puN kernel/irq/manage.c~uml-gen-irq-release kernel/irq/manage.c
> --- linux-2.6.git/kernel/irq/manage.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
> +++ linux-2.6.git-paolo/kernel/irq/manage.c	2005-05-25 01:15:46.000000000 +0200
> @@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *de
>  
>  			/* Found it - now remove it from the list of entries */
>  			*pp = action->next;
> +
> +			if (desc->handler->release)
> +				desc->handler->release(irq, dev_id);
> +

Because right now we know the *only* port that needs a release method
is UML I wonder if we could do save a couple of bytes & cycles for
everyone else by doing something like #ifdef CONFIG_IRQ_HAS_RELEASE,
#endif around that and then letting the Kconfig magic set
CONFIG_IRQ_HAS_RELEASE as required?  If other arches need it thay can
do the same and if eventually almost everyone does we can kill the
#ifdef crud?

Longer term I wonder if some of the irq mechanics in UML couldn't end
up being a bit more like the s390 stuff too?


-------------------------------------------------------
This SF.Net email is sponsored by Yahoo.
Introducing Yahoo! Search Developer Network - Create apps using Yahoo!
Search APIs Find out how you can build Yahoo! directly into your own
Applications - visit http://developer.yahoo.net/?fr=offad-ysdn-ostg-q22005
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

[uml-devel] Re: [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[Blaisorblade]

On Friday 27 May 2005 04:11, Chris Wedgwood wrote:
> On Fri, May 27, 2005 at 02:39:26AM +0200, blaisorblade@yahoo.it wrote:
> > From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>, Chris
> > Wedgwood <cw@f00f.org> CC: Ingo Molnar <mingo@redhat.com>
>
> [...]
>
> > This is heavily based on some work by Chris Wedgwood, which however
> > didn't get the patch merged for something I'd call a
> > "misunderstanding" (the need for this patch wasn't cleanly
> > explained, thus adding the generic hook was felt as undesirable).

> Looks very reasonable to me and your explaination is much better than
> mine was :-)
Yes, it took some time to me to go working on this and getting the time to 
explain it clearly.
> > diff -puN kernel/irq/manage.c~uml-gen-irq-release kernel/irq/manage.c
> > --- linux-2.6.git/kernel/irq/manage.c~uml-gen-irq-release	2005-05-25
> > 01:15:46.000000000 +0200 +++
> > linux-2.6.git-paolo/kernel/irq/manage.c	2005-05-25 01:15:46.000000000
> > +0200 @@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *de
> >
> >  			/* Found it - now remove it from the list of entries */
> >  			*pp = action->next;
> > +
> > +			if (desc->handler->release)
> > +				desc->handler->release(irq, dev_id);
> > +
>
> Because right now we know the *only* port that needs a release method
> is UML I wonder if we could do save a couple of bytes & cycles for
> everyone else by doing something like #ifdef CONFIG_IRQ_HAS_RELEASE,
> #endif around that and then letting the Kconfig magic set
> CONFIG_IRQ_HAS_RELEASE as required?  If other arches need it thay can
> do the same and if eventually almost everyone does we can kill the
> #ifdef crud?
Well, that's a point, even because a conditional jump needs to flush the 
pipeline when mispredicted (which won't happen on other ARCHs after the 
initial period, if this jump stays in the Branch Target Buffers).
> Longer term I wonder if some of the irq mechanics in UML couldn't end
> up being a bit more like the s390 stuff too?
Christoph Hellwig too suggested this, however anything such *must* be longer 
term (while this was earlier pointed as a reason to drop this patch, last 
time).
Beyond that, I've not a clear understanding of S390, so I cannot for now help 
(including any merit discussion) on this point... Bodo Stroesser is porting 
UML on S390 so probably he might help more on this point.
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade

	

	
		
___________________________________ 
Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB 
http://mail.yahoo.it



-------------------------------------------------------
This SF.Net email is sponsored by Yahoo.
Introducing Yahoo! Search Developer Network - Create apps using Yahoo!
Search APIs Find out how you can build Yahoo! directly into your own
Applications - visit http://developer.yahoo.net/?fr=offad-ysdn-ostg-q22005
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel

[uml-devel] Re: [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[Chris Wedgwood]

On Sat, May 28, 2005 at 01:26:15PM +0200, Blaisorblade wrote:

> Well, that's a point, even because a conditional jump needs to flush
> the pipeline when mispredicted (which won't happen on other ARCHs
> after the initial period, if this jump stays in the Branch Target
> Buffers).

Because it's crud we are accumulating over time that nobody except UML
needs and maybe one day UML won't need it.  Also #ifdef's (though
ugly) would make it much more likely that it goes away when it can.


-------------------------------------------------------
This SF.Net email is sponsored by Yahoo.
Introducing Yahoo! Search Developer Network - Create apps using Yahoo!
Search APIs Find out how you can build Yahoo! directly into your own
Applications - visit http://developer.yahoo.net/?fr=offad-ysdn-ostg-q22005
_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel