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Subject[PATCH] vhost: Don't use defined in VHOST_ARCH_CAN_ACCEL_UACCESS definition
Date
Clang warns:

drivers/vhost/vhost.c:2085:5: warning: macro expansion producing
'defined' has undefined behavior [-Wexpansion-to-defined]
#if VHOST_ARCH_CAN_ACCEL_UACCESS
^
drivers/vhost/vhost.h:98:38: note: expanded from macro
'VHOST_ARCH_CAN_ACCEL_UACCESS'
#define VHOST_ARCH_CAN_ACCEL_UACCESS defined(CONFIG_MMU_NOTIFIER) && \
^

Rework VHOST_ARCH_CAN_ACCEL_UACCESS to be defined under those conditions
so that the meaning of the code doesn't change and clang no longer
warns.

Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
Link: https://github.com/ClangBuiltLinux/linux/issues/508
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
drivers/vhost/vhost.c | 44 +++++++++++++++++++++----------------------
drivers/vhost/vhost.h | 7 ++++---
2 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index dc9301d31f12..cc56d08b4275 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -299,7 +299,7 @@ static void vhost_vq_meta_reset(struct vhost_dev *d)
__vhost_vq_meta_reset(d->vqs[i]);
}

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_map_unprefetch(struct vhost_map *map)
{
kfree(map->pages);
@@ -483,7 +483,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
vq->iotlb = NULL;
vq->invalidate_count = 0;
__vhost_vq_meta_reset(vq);
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_reset_vq_maps(vq);
#endif
}
@@ -635,7 +635,7 @@ void vhost_dev_init(struct vhost_dev *dev,
INIT_LIST_HEAD(&dev->read_list);
INIT_LIST_HEAD(&dev->pending_list);
spin_lock_init(&dev->iotlb_lock);
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_init_maps(dev);
#endif

@@ -726,7 +726,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
if (err)
goto err_cgroup;

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
err = mmu_notifier_register(&dev->mmu_notifier, dev->mm);
if (err)
goto err_mmu_notifier;
@@ -734,7 +734,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)

return 0;

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
err_mmu_notifier:
vhost_dev_free_iovecs(dev);
#endif
@@ -828,7 +828,7 @@ static void vhost_clear_msg(struct vhost_dev *dev)
spin_unlock(&dev->iotlb_lock);
}

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_setup_uaddr(struct vhost_virtqueue *vq,
int index, unsigned long uaddr,
size_t size, bool write)
@@ -959,12 +959,12 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
dev->worker = NULL;
}
if (dev->mm) {
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
mmu_notifier_unregister(&dev->mmu_notifier, dev->mm);
#endif
mmput(dev->mm);
}
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
for (i = 0; i < dev->nvqs; i++)
vhost_uninit_vq_maps(dev->vqs[i]);
#endif
@@ -1196,7 +1196,7 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,

static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;

@@ -1224,7 +1224,7 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
struct vring_used_elem *head, int idx,
int count)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
size_t size;
@@ -1252,7 +1252,7 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)

{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;

@@ -1278,7 +1278,7 @@ static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)

{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;

@@ -1342,7 +1342,7 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d)
static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;

@@ -1367,7 +1367,7 @@ static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
__virtio16 *head, int idx)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;

@@ -1393,7 +1393,7 @@ static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
__virtio16 *flags)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;

@@ -1418,7 +1418,7 @@ static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
__virtio16 *event)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;

@@ -1441,7 +1441,7 @@ static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;

@@ -1466,7 +1466,7 @@ static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
static inline int vhost_get_desc(struct vhost_virtqueue *vq,
struct vring_desc *desc, int idx)
{
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_desc *d;

@@ -1825,7 +1825,7 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq,
return true;
}

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_vq_map_prefetch(struct vhost_virtqueue *vq)
{
struct vhost_map __rcu *map;
@@ -1846,7 +1846,7 @@ int vq_meta_prefetch(struct vhost_virtqueue *vq)
unsigned int num = vq->num;

if (!vq->iotlb) {
-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_vq_map_prefetch(vq);
#endif
return 1;
@@ -2061,7 +2061,7 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,

mutex_lock(&vq->mutex);

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
/* Unregister MMU notifer to allow invalidation callback
* can access vq->uaddrs[] without holding a lock.
*/
@@ -2082,7 +2082,7 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
BUG();
}

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_setup_vq_uaddr(vq);

if (d->mm)
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index c5d950cf7627..d9f36c479fa7 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -95,8 +95,9 @@ struct vhost_uaddr {
bool write;
};

-#define VHOST_ARCH_CAN_ACCEL_UACCESS defined(CONFIG_MMU_NOTIFIER) && \
- ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
+#if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
+#define VHOST_ARCH_CAN_ACCEL_UACCESS
+#endif

/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {
@@ -109,7 +110,7 @@ struct vhost_virtqueue {
struct vring_avail __user *avail;
struct vring_used __user *used;

-#if VHOST_ARCH_CAN_ACCEL_UACCESS
+#ifdef VHOST_ARCH_CAN_ACCEL_UACCESS
/* Read by memory accessors, modified by meta data
* prefetching, MMU notifier and vring ioctl().
* Synchonrized through mmu_lock (writers) and RCU (writers
--
2.22.0.rc3
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