ida: make ida_simple_get/put() IRQ safe

It's often convenient to be able to release resource from IRQ context.
Make ida_simple_*() use irqsave/restore spin ops so that they are IRQ
safe.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/idr.c

@@ -944,6 +944,7 @@ int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end,
 {
 	int ret, id;
 	unsigned int max;
+	unsigned long flags;
 
 	BUG_ON((int)start < 0);
 	BUG_ON((int)end < 0);
@@ -959,7 +960,7 @@ again:
 	if (!ida_pre_get(ida, gfp_mask))
 		return -ENOMEM;
 
-	spin_lock(&simple_ida_lock);
+	spin_lock_irqsave(&simple_ida_lock, flags);
 	ret = ida_get_new_above(ida, start, &id);
 	if (!ret) {
 		if (id > max) {
@@ -969,7 +970,7 @@ again:
 			ret = id;
 		}
 	}
-	spin_unlock(&simple_ida_lock);
+	spin_unlock_irqrestore(&simple_ida_lock, flags);
 
 	if (unlikely(ret == -EAGAIN))
 		goto again;
@@ -985,10 +986,12 @@ EXPORT_SYMBOL(ida_simple_get);
  */
 void ida_simple_remove(struct ida *ida, unsigned int id)
 {
+	unsigned long flags;
+
 	BUG_ON((int)id < 0);
-	spin_lock(&simple_ida_lock);
+	spin_lock_irqsave(&simple_ida_lock, flags);
 	ida_remove(ida, id);
-	spin_unlock(&simple_ida_lock);
+	spin_unlock_irqrestore(&simple_ida_lock, flags);
 }
 EXPORT_SYMBOL(ida_simple_remove);