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* [PATCH] vhost: fix external message handlers
@ 2022-03-07 18:11 David Marchand
  2022-03-08  8:34 ` Maxime Coquelin
  2022-03-08  9:44 ` [PATCH v2] " David Marchand
  0 siblings, 2 replies; 9+ messages in thread
From: David Marchand @ 2022-03-07 18:11 UTC (permalink / raw)
  To: dev, roy.fan.zhang, Maxime Coquelin, Chenbo Xia, Christophe Fontaine

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.marchand@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


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2022-03-08 15:07 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-03-07 18:11 [PATCH] vhost: fix external message handlers David Marchand
2022-03-08  8:34 ` Maxime Coquelin
2022-03-08  8:37   ` David Marchand
2022-03-08  8:39     ` Maxime Coquelin
2022-03-08  9:44 ` [PATCH v2] " David Marchand
2022-03-08 10:44   ` Maxime Coquelin
2022-03-08 14:04     ` Poczatek, Jakub
2022-03-08 14:47   ` Christophe Fontaine
2022-03-08 15:06   ` David Marchand

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