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Tue, 08 Mar 2022 03:34:30 -0500 X-MC-Unique: L2BV6-mONR250V6qlUriMQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 74ED68066F3; Tue, 8 Mar 2022 08:34:29 +0000 (UTC) Received: from [10.39.208.21] (unknown [10.39.208.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E0A7F519C9; Tue, 8 Mar 2022 08:34:17 +0000 (UTC) Message-ID: <2db1dea9-43e3-9ffa-5dcf-f1bc9d2c7315@redhat.com> Date: Tue, 8 Mar 2022 09:34:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] vhost: fix external message handlers To: David Marchand , dev@dpdk.org, roy.fan.zhang@intel.com, Chenbo Xia , Christophe Fontaine References: <20220307181101.10394-1-david.marchand@redhat.com> From: Maxime Coquelin In-Reply-To: <20220307181101.10394-1-david.marchand@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=maxime.coquelin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org 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 > --- > 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 We may also add Reported-by tag when applying. Thanks! Maxime