[PATCH] uml: irq locking fixes

As the comment immediately preceding this points out, this list is changed in
irq context, so it needs to be protected with spin_lock_irqsave in process
context when it is processed.

Sometimes, gcc should just compile the comments and forget the code.

The IRQ side of this was better, in the sense that it blocked and unblocked
interrupts, but it still should have saved and restored them.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 7b8baf146acc..9fdfad649536 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -236,11 +236,11 @@ void free_irqs(void)
         struct chan *chan;
         LIST_HEAD(list);
         struct list_head *ele;
+        unsigned long flags;
 
-        spin_lock_irq(&irqs_to_free_lock);
+        spin_lock_irqsave(&irqs_to_free_lock, flags);
         list_splice_init(&irqs_to_free, &list);
-        INIT_LIST_HEAD(&irqs_to_free);
-        spin_unlock_irq(&irqs_to_free_lock);
+        spin_unlock_irqrestore(&irqs_to_free_lock, flags);
 
         list_for_each(ele, &list){
                 chan = list_entry(ele, struct chan, free_list);
@@ -255,13 +255,15 @@ void free_irqs(void)
 
 static void close_one_chan(struct chan *chan, int delay_free_irq)
 {
+        unsigned long flags;
+
         if(!chan->opened)
                 return;
 
         if(delay_free_irq){
-                spin_lock_irq(&irqs_to_free_lock);
+                spin_lock_irqsave(&irqs_to_free_lock, flags);
                 list_add(&chan->free_list, &irqs_to_free);
-                spin_unlock_irq(&irqs_to_free_lock);
+                spin_unlock_irqrestore(&irqs_to_free_lock, flags);
         }
         else {
                 if(chan->input)