[PATCH] uml: add and use generic hw_controller_type->release

With Chris Wedgwood <cw@f00f.org>

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>
CC: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

8 files changed, 12 insertions, 11 deletions

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 025d3be8aca4..562f864254ba 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -406,14 +406,12 @@ void line_disable(struct tty_struct *tty, int current_irq)
 	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 --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index 4eeaf88c1e97..5388a7428691 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -146,7 +146,6 @@ static int uml_net_close(struct net_device *dev)
 	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 --git a/arch/um/drivers/port_kern.c b/arch/um/drivers/port_kern.c
index b5ee07472f79..c41efd207fcc 100644
--- a/arch/um/drivers/port_kern.c
+++ b/arch/um/drivers/port_kern.c
@@ -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 --git a/arch/um/drivers/xterm_kern.c b/arch/um/drivers/xterm_kern.c
index a4fdf3584ad2..d269a80f4b0c 100644
--- a/arch/um/drivers/xterm_kern.c
+++ b/arch/um/drivers/xterm_kern.c
@@ -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 --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index d44fb5282547..9f18061ef4c9 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -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_irq_type = {
 
 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);
 	}
 }
diff --git a/arch/um/kernel/irq_user.c b/arch/um/kernel/irq_user.c
index b3074cbaa479..c3ccaf24f3e0 100644
--- a/arch/um/kernel/irq_user.c
+++ b/arch/um/kernel/irq_user.c
@@ -85,8 +85,6 @@ void sigio_handler(int sig, union uml_pt_regs *regs)
 				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 --git a/include/linux/irq.h b/include/linux/irq.h
index c3ff4d101667..b68ad80e2464 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -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 --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5202e4c4a5b6..5fde8177eedf 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *dev_id)
 
 			/* 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)