Merge branch 'ptr_ring-fixes'

Michael S. Tsirkin says:

====================
ptr_ring fixes

This fixes a bunch of issues around ptr_ring use in net core.
One of these: "tap: fix use-after-free" is also needed on net,
but can't be backported cleanly.

I will post a net patch separately.

Lightly tested - Jason, could you pls confirm this
addresses the security issue you saw with ptr_ring?
Testing reports would be appreciated too.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Jason Wang <jasowang@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

4 files changed, 61 insertions, 3 deletions

diff --git a/tools/virtio/linux/kernel.h b/tools/virtio/linux/kernel.h
index 395521a7a8d8..fca8381bbe04 100644
--- a/tools/virtio/linux/kernel.h
+++ b/tools/virtio/linux/kernel.h
@@ -118,7 +118,7 @@ static inline void free_page(unsigned long addr)
 #define dev_err(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)
 #define dev_warn(dev, format, ...) fprintf (stderr, format, ## __VA_ARGS__)
 
-#define WARN_ON_ONCE(cond) ((cond) && fprintf (stderr, "WARNING\n"))
+#define WARN_ON_ONCE(cond) ((cond) ? fprintf (stderr, "WARNING\n") : 0)
 
 #define min(x, y) ({				\
 	typeof(x) _min1 = (x);			\
diff --git a/tools/virtio/linux/thread_info.h b/tools/virtio/linux/thread_info.h
new file mode 100644
index 000000000000..e0f610d08006
--- /dev/null
+++ b/tools/virtio/linux/thread_info.h
@@ -0,0 +1 @@
+#define check_copy_size(A, B, C) (1)
diff --git a/tools/virtio/ringtest/main.h b/tools/virtio/ringtest/main.h
index 5706e075adf2..301d59bfcd0a 100644
--- a/tools/virtio/ringtest/main.h
+++ b/tools/virtio/ringtest/main.h
@@ -111,7 +111,7 @@ static inline void busy_wait(void)
 } 
 
 #if defined(__x86_64__) || defined(__i386__)
-#define smp_mb()     asm volatile("lock; addl $0,-128(%%rsp)" ::: "memory", "cc")
+#define smp_mb()     asm volatile("lock; addl $0,-132(%%rsp)" ::: "memory", "cc")
 #else
 /*
  * Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
@@ -134,4 +134,61 @@ static inline void busy_wait(void)
     barrier(); \
 } while (0)
 
+#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__)
+#define smp_wmb() barrier()
+#else
+#define smp_wmb() smp_release()
+#endif
+
+#ifdef __alpha__
+#define smp_read_barrier_depends() smp_acquire()
+#else
+#define smp_read_barrier_depends() do {} while(0)
+#endif
+
+static __always_inline
+void __read_once_size(const volatile void *p, void *res, int size)
+{
+        switch (size) {                                                 \
+        case 1: *(unsigned char *)res = *(volatile unsigned char *)p; break;              \
+        case 2: *(unsigned short *)res = *(volatile unsigned short *)p; break;            \
+        case 4: *(unsigned int *)res = *(volatile unsigned int *)p; break;            \
+        case 8: *(unsigned long long *)res = *(volatile unsigned long long *)p; break;            \
+        default:                                                        \
+                barrier();                                              \
+                __builtin_memcpy((void *)res, (const void *)p, size);   \
+                barrier();                                              \
+        }                                                               \
+}
+
+static __always_inline void __write_once_size(volatile void *p, void *res, int size)
+{
+	switch (size) {
+	case 1: *(volatile unsigned char *)p = *(unsigned char *)res; break;
+	case 2: *(volatile unsigned short *)p = *(unsigned short *)res; break;
+	case 4: *(volatile unsigned int *)p = *(unsigned int *)res; break;
+	case 8: *(volatile unsigned long long *)p = *(unsigned long long *)res; break;
+	default:
+		barrier();
+		__builtin_memcpy((void *)p, (const void *)res, size);
+		barrier();
+	}
+}
+
+#define READ_ONCE(x) \
+({									\
+	union { typeof(x) __val; char __c[1]; } __u;			\
+	__read_once_size(&(x), __u.__c, sizeof(x));		\
+	smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
+	__u.__val;							\
+})
+
+#define WRITE_ONCE(x, val) \
+({							\
+	union { typeof(x) __val; char __c[1]; } __u =	\
+		{ .__val = (typeof(x)) (val) }; \
+	__write_once_size(&(x), __u.__c, sizeof(x));	\
+	__u.__val;					\
+})
+
 #endif
diff --git a/tools/virtio/ringtest/ptr_ring.c b/tools/virtio/ringtest/ptr_ring.c
index e6e81305ef46..477899c12c51 100644
--- a/tools/virtio/ringtest/ptr_ring.c
+++ b/tools/virtio/ringtest/ptr_ring.c
@@ -187,7 +187,7 @@ bool enable_kick()
 
 bool avail_empty()
 {
-	return !__ptr_ring_peek(&array);
+	return __ptr_ring_empty(&array);
 }
 
 bool use_buf(unsigned *lenp, void **bufp)