Following a rework, external message handlers were receiving a pointer
to a vhost_user message (as stated in the API), but lost the ability to
interact with fds attached to the message.
Restore the original layout and put a build check and reminders.
Bugzilla ID: 953
Fixes: 5e0099dc709e ("vhost: remove payload size limitation")
Signed-off-by: David Marchand <david.march...@redhat.com>
---
This patch is untested, but sending quickly to get feedback from the
reporter and comments from author and maintainers.
---
lib/vhost/vhost_user.c | 8 ++++----
lib/vhost/vhost_user.h | 7 +++++--
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 723c6890c3..589b950458 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -3023,8 +3023,8 @@ vhost_user_msg_handler(int vid, int fd)
handled = false;
if (dev->extern_ops.pre_msg_handle) {
- ret = (*dev->extern_ops.pre_msg_handle)(dev->vid,
- (void *)&ctx.msg);
+ RTE_BUILD_BUG_ON(offsetof(struct vhu_msg_context, msg) != 0);
+ ret = (*dev->extern_ops.pre_msg_handle)(dev->vid, &ctx);
switch (ret) {
case RTE_VHOST_MSG_RESULT_REPLY:
send_vhost_reply(dev, fd, &ctx);
@@ -3069,8 +3069,8 @@ vhost_user_msg_handler(int vid, int fd)
skip_to_post_handle:
if (ret != RTE_VHOST_MSG_RESULT_ERR &&
dev->extern_ops.post_msg_handle) {
- ret = (*dev->extern_ops.post_msg_handle)(dev->vid,
- (void *)&ctx.msg);
+ RTE_BUILD_BUG_ON(offsetof(struct vhu_msg_context, msg) != 0);
+ ret = (*dev->extern_ops.post_msg_handle)(dev->vid, &ctx);
switch (ret) {
case RTE_VHOST_MSG_RESULT_REPLY:
send_vhost_reply(dev, fd, &ctx);
diff --git a/lib/vhost/vhost_user.h b/lib/vhost/vhost_user.h
index be53669f3b..555f89c97a 100644
--- a/lib/vhost/vhost_user.h
+++ b/lib/vhost/vhost_user.h
@@ -152,10 +152,13 @@ typedef struct VhostUserMsg {
/* Nothing should be added after the payload */
} __rte_packed VhostUserMsg;
-struct vhu_msg_context {
+/* Note: this structure and VhostUserMsg can't be changed carelessly as
+ * external message handlers rely on them.
+ */
+__rte_packed struct vhu_msg_context {
+ VhostUserMsg msg;
int fds[VHOST_MEMORY_MAX_NREGIONS];
int fd_num;
- VhostUserMsg msg;
};
#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
--
2.23.0
