diff --git a/net/9p/util.c b/net/9p/util.c
index 22077b7..ef72155 100644
--- a/net/9p/util.c
+++ b/net/9p/util.c
@@ -33,7 +33,7 @@
 #include <net/9p/9p.h>
 
 struct p9_idpool {
-	struct semaphore lock;
+	spinlock_t lock;
 	struct idr pool;
 };
 
@@ -45,7 +45,7 @@
 	if (!p)
 		return ERR_PTR(-ENOMEM);
 
-	init_MUTEX(&p->lock);
+	spin_lock_init(&p->lock);
 	idr_init(&p->pool);
 
 	return p;
@@ -71,19 +71,17 @@
 {
 	int i = 0;
 	int error;
+	unsigned int flags;
 
 retry:
 	if (idr_pre_get(&p->pool, GFP_KERNEL) == 0)
 		return 0;
 
-	if (down_interruptible(&p->lock) == -EINTR) {
-		P9_EPRINTK(KERN_WARNING, "Interrupted while locking\n");
-		return -1;
-	}
+	spin_lock_irqsave(&p->lock, flags);
 
 	/* no need to store exactly p, we just need something non-null */
 	error = idr_get_new(&p->pool, p, &i);
-	up(&p->lock);
+	spin_unlock_irqrestore(&p->lock, flags);
 
 	if (error == -EAGAIN)
 		goto retry;
@@ -104,12 +102,10 @@
 
 void p9_idpool_put(int id, struct p9_idpool *p)
 {
-	if (down_interruptible(&p->lock) == -EINTR) {
-		P9_EPRINTK(KERN_WARNING, "Interrupted while locking\n");
-		return;
-	}
+	unsigned int flags;
+	spin_lock_irqsave(&p->lock, flags);
 	idr_remove(&p->pool, id);
-	up(&p->lock);
+	spin_unlock_irqrestore(&p->lock, flags);
 }
 EXPORT_SYMBOL(p9_idpool_put);