[PATCH 2/2] tools/virtio: check posix_memalign() for failure

[Liam R. Howlett (Google)]

posix_memalign() returns zero or a positive error number and does not set
errno.  virtio_test and vhost_net_test assert that the return is not
negative, which will always be true, and the userspace __get_free_page()
ignores it, so a failed allocation continues without setting the pointer

Assert a zero return in the tests, and return 0 from __get_free_page() on
failure, as the kernel's does.

Signed-off-by: Liam R. Howlett (Google) <liam@xxxxxxxxxxxxx>
---
 tools/virtio/linux/kernel.h   | 3 ++-
 tools/virtio/vhost_net_test.c | 2 +-
 tools/virtio/virtio_test.c    | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/virtio/linux/kernel.h b/tools/virtio/linux/kernel.h
index 104abf9d1aee5..3497660c690a9 100644
--- a/tools/virtio/linux/kernel.h
+++ b/tools/virtio/linux/kernel.h
@@ -106,7 +106,8 @@ static inline unsigned long __get_free_page(gfp_t gfp)
 {
 	void *p;
 
-	posix_memalign(&p, PAGE_SIZE, PAGE_SIZE);
+	if (posix_memalign(&p, PAGE_SIZE, PAGE_SIZE))
+		return 0;
 	return (unsigned long)p;
 }
 
diff --git a/tools/virtio/vhost_net_test.c b/tools/virtio/vhost_net_test.c
index 566e15420bb65..3122ea0970568 100644
--- a/tools/virtio/vhost_net_test.c
+++ b/tools/virtio/vhost_net_test.c
@@ -197,7 +197,7 @@ static void vq_info_add(struct vdev_info *dev, int idx, int num, int fd)
 	info->idx = idx;
 	info->kick = eventfd(0, EFD_NONBLOCK);
 	r = posix_memalign(&info->ring, 4096, vring_size(num, 4096));
-	assert(r >= 0);
+	assert(!r);
 	vq_reset(info, num, &dev->vdev);
 	vhost_vq_setup(dev, info);
 
diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
index 028f54e6854a8..9d61463f6e09b 100644
--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c
@@ -116,7 +116,7 @@ static void vq_info_add(struct vdev_info *dev, int num)
 	info->kick = eventfd(0, EFD_NONBLOCK);
 	info->call = eventfd(0, EFD_NONBLOCK);
 	r = posix_memalign(&info->ring, 4096, vring_size(num, 4096));
-	assert(r >= 0);
+	assert(!r);
 	vq_reset(info, num, &dev->vdev);
 	vhost_vq_setup(dev, info);
 	dev->fds[info->idx].fd = info->call;
-- 
2.47.3