ptr_ring: fix up after recent ptr_ring changes

Add more stubs to make it build.

Fixes: 81fbfe8a ("ptr_ring: use kmalloc_array()")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

tools/virtio/ringtest/ptr_ring.c

@@ -16,24 +16,41 @@
 #define unlikely(x)    (__builtin_expect(!!(x), 0))
 #define likely(x)    (__builtin_expect(!!(x), 1))
 #define ALIGN(x, a) (((x) + (a) - 1) / (a) * (a))
+#define SIZE_MAX        (~(size_t)0)
+
 typedef pthread_spinlock_t  spinlock_t;
 
 typedef int gfp_t;
-static void *kmalloc(unsigned size, gfp_t gfp)
-{
-	return memalign(64, size);
-}
+#define __GFP_ZERO 0x1
 
-static void *kzalloc(unsigned size, gfp_t gfp)
+static void *kmalloc(unsigned size, gfp_t gfp)
 {
 	void *p = memalign(64, size);
 	if (!p)
 		return p;
-	memset(p, 0, size);
 
+	if (gfp & __GFP_ZERO)
+		memset(p, 0, size);
 	return p;
 }
 
+static inline void *kzalloc(unsigned size, gfp_t flags)
+{
+	return kmalloc(size, flags | __GFP_ZERO);
+}
+
+static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
+{
+	if (size != 0 && n > SIZE_MAX / size)
+		return NULL;
+	return kmalloc(n * size, flags);
+}
+
+static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+{
+	return kmalloc_array(n, size, flags | __GFP_ZERO);
+}
+
 static void kfree(void *p)
 {
 	if (p)