diff mbox series

vhost: fix external message handlers

Message ID 20220307181101.10394-1-david.marchand@redhat.com (mailing list archive)
State Superseded, archived
Delegated to: Maxime Coquelin
Headers
Series vhost: fix external message handlers |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/github-robot: build fail github build: failed
ci/iol-mellanox-Performance success Performance Testing PASS
ci/Intel-compilation fail Compilation issues
ci/intel-Testing success Testing PASS
ci/iol-aarch64-unit-testing fail Testing issues
ci/iol-x86_64-compile-testing fail Testing issues
ci/iol-aarch64-compile-testing fail Testing issues
ci/iol-x86_64-unit-testing fail Testing issues
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-abi-testing success Testing PASS

Commit Message

David Marchand March 7, 2022, 6:11 p.m. UTC 
  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(-)

Comments

Maxime Coquelin March 8, 2022, 8:34 a.m. UTC | #1 
Hi,

On 3/7/22 19:11, David Marchand wrote:
> 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)

We should revisit the callbacks prototype when we'll be allowed to break
API, passing the message pointer as void * is definitely not a good
idea.

In the mean time, I agree with your fix:

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

We may also add Reported-by tag when applying.

Thanks!
Maxime
David Marchand March 8, 2022, 8:37 a.m. UTC | #2 
On Tue, Mar 8, 2022 at 9:34 AM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> On 3/7/22 19:11, David Marchand wrote:
> > 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)
>
> We should revisit the callbacks prototype when we'll be allowed to break
> API, passing the message pointer as void * is definitely not a good
> idea.

Indeed.

>
> In the mean time, I agree with your fix:
>
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>
> We may also add Reported-by tag when applying.

There is an issue with clang, I'll send a v2.
Maxime Coquelin March 8, 2022, 8:39 a.m. UTC | #3 
On 3/8/22 09:37, David Marchand wrote:
> On Tue, Mar 8, 2022 at 9:34 AM Maxime Coquelin
> <maxime.coquelin@redhat.com> wrote:
>> On 3/7/22 19:11, David Marchand wrote:
>>> 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)
>>
>> We should revisit the callbacks prototype when we'll be allowed to break
>> API, passing the message pointer as void * is definitely not a good
>> idea.
> 
> Indeed.
> 
>>
>> In the mean time, I agree with your fix:
>>
>> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>
>> We may also add Reported-by tag when applying.
> 
> There is an issue with clang, I'll send a v2.
> 

Ok.
Fan, can you have a try and confirm it fixes the issue on your side?

Thanks,
Maxime
diff mbox series

Patch

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)