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Subject[PATCH 4/6] UML - Lock the irqs_to_free list
Date
From
Fix (i.e. add some) the locking around the irqs_to_free list.

Signed-off-by: Jeff Dike <jdike@addtoit.com>

--
arch/um/drivers/chan_kern.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)

Index: linux-2.6.18-mm/arch/um/drivers/chan_kern.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/drivers/chan_kern.c 2006-12-29 15:27:16.000000000 -0500
+++ linux-2.6.18-mm/arch/um/drivers/chan_kern.c 2006-12-29 16:38:43.000000000 -0500
@@ -222,15 +222,28 @@ void enable_chan(struct line *line)
}
}

+/* Items are added in IRQ context, when free_irq can't be called, and
+ * removed in process context, when it can.
+ * This handles interrupt sources which disappear, and which need to
+ * be permanently disabled. This is discovered in IRQ context, but
+ * the freeing of the IRQ must be done later.
+ */
+static DEFINE_SPINLOCK(irqs_to_free_lock);
static LIST_HEAD(irqs_to_free);

void free_irqs(void)
{
struct chan *chan;
+ LIST_HEAD(list);
+ struct list_head *ele;
+
+ spin_lock_irq(&irqs_to_free_lock);
+ list_splice_init(&irqs_to_free, &list);
+ INIT_LIST_HEAD(&irqs_to_free);
+ spin_unlock_irq(&irqs_to_free_lock);

- while(!list_empty(&irqs_to_free)){
- chan = list_entry(irqs_to_free.next, struct chan, free_list);
- list_del(&chan->free_list);
+ list_for_each(ele, &list){
+ chan = list_entry(ele, struct chan, free_list);

if(chan->input)
free_irq(chan->line->driver->read_irq, chan);
@@ -246,7 +259,9 @@ static void close_one_chan(struct chan *
return;

if(delay_free_irq){
+ spin_lock_irq(&irqs_to_free_lock);
list_add(&chan->free_list, &irqs_to_free);
+ spin_unlock_irq(&irqs_to_free_lock);
}
else {
if(chan->input)
-
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