A simple comment in vhost_user_msg_handler() is not that robust.

Add a lock_all_qps property to message handlers so that their
implementation can add a build check and assert a vq is locked.

Signed-off-by: David Marchand <david.march...@redhat.com>
Acked-by: Eelco Chaudron <echau...@redhat.com>
Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
Changes since v1:
- moved this patch as the last of the series,

---
 lib/vhost/vhost_user.c | 114 +++++++++++++++++++----------------------
 1 file changed, 53 insertions(+), 61 deletions(-)

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 651ea5854b..e8020ccfd3 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -56,14 +56,24 @@
 #define INFLIGHT_ALIGNMENT     64
 #define INFLIGHT_VERSION       0x1
 
-typedef struct vhost_message_handler {
+typedef const struct vhost_message_handler {
        const char *description;
        int (*callback)(struct virtio_net **pdev, struct vhu_msg_context *ctx,
                int main_fd);
        bool accepts_fd;
+       bool lock_all_qps;
 } vhost_message_handler_t;
 static vhost_message_handler_t vhost_message_handlers[];
 
+/* vhost_user_msg_handler() locks all qps based on a handler's lock_all_qps.
+ * Later, a handler may need to ensure the vq has been locked (for example,
+ * when calling lock annotated helpers).
+ */
+#define VHOST_USER_ASSERT_LOCK(dev, vq, id) do { \
+       RTE_BUILD_BUG_ON(!vhost_message_handlers[id].lock_all_qps); \
+       vq_assert_lock(dev, vq); \
+} while (0)
+
 static int send_vhost_reply(struct virtio_net *dev, int sockfd, struct 
vhu_msg_context *ctx);
 static int read_vhost_message(struct virtio_net *dev, int sockfd, struct 
vhu_msg_context *ctx);
 
@@ -400,7 +410,7 @@ vhost_user_set_features(struct virtio_net **pdev,
                        cleanup_vq(vq, 1);
                        cleanup_vq_inflight(dev, vq);
                        /* vhost_user_lock_all_queue_pairs locked all qps */
-                       vq_assert_lock(dev, vq);
+                       VHOST_USER_ASSERT_LOCK(dev, vq, 
VHOST_USER_SET_FEATURES);
                        rte_rwlock_write_unlock(&vq->access_lock);
                        free_vq(dev, vq);
                }
@@ -927,7 +937,7 @@ vhost_user_set_vring_addr(struct virtio_net **pdev,
        vq = dev->virtqueue[ctx->msg.payload.addr.index];
 
        /* vhost_user_lock_all_queue_pairs locked all qps */
-       vq_assert_lock(dev, vq);
+       VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_VRING_ADDR);
 
        access_ok = vq->access_ok;
 
@@ -1442,7 +1452,7 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
 
                if (vq->desc || vq->avail || vq->used) {
                        /* vhost_user_lock_all_queue_pairs locked all qps */
-                       vq_assert_lock(dev, vq);
+                       VHOST_USER_ASSERT_LOCK(dev, vq, 
VHOST_USER_SET_MEM_TABLE);
 
                        /*
                         * If the memory table got updated, the ring addresses
@@ -2234,7 +2244,7 @@ vhost_user_set_vring_enable(struct virtio_net **pdev,
        vq = dev->virtqueue[index];
        if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
                /* vhost_user_lock_all_queue_pairs locked all qps */
-               vq_assert_lock(dev, vq);
+               VHOST_USER_ASSERT_LOCK(dev, vq, VHOST_USER_SET_VRING_ENABLE);
                if (enable && vq->async && vq->async->pkts_inflight_n) {
                        VHOST_LOG_CONFIG(dev->ifname, ERR,
                                "failed to enable vring. Inflight packets must 
be completed first\n");
@@ -2839,41 +2849,43 @@ vhost_user_set_status(struct virtio_net **pdev,
 }
 
 #define VHOST_MESSAGE_HANDLERS \
-VHOST_MESSAGE_HANDLER(VHOST_USER_NONE, NULL, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_FEATURES, vhost_user_get_features, false) 
\
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_FEATURES, vhost_user_set_features, false) 
\
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_OWNER, vhost_user_set_owner, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_OWNER, vhost_user_reset_owner, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_MEM_TABLE, vhost_user_set_mem_table, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_BASE, vhost_user_set_log_base, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_FD, vhost_user_set_log_fd, true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_NUM, vhost_user_set_vring_num, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ADDR, vhost_user_set_vring_addr, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_BASE, vhost_user_set_vring_base, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_VRING_BASE, vhost_user_get_vring_base, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_KICK, vhost_user_set_vring_kick, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_CALL, vhost_user_set_vring_call, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ERR, vhost_user_set_vring_err, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_PROTOCOL_FEATURES, 
vhost_user_get_protocol_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_PROTOCOL_FEATURES, 
vhost_user_set_protocol_features, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_QUEUE_NUM, vhost_user_get_queue_num, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ENABLE, 
vhost_user_set_vring_enable, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SEND_RARP, vhost_user_send_rarp, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_NET_SET_MTU, vhost_user_net_set_mtu, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_BACKEND_REQ_FD, vhost_user_set_req_fd, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_IOTLB_MSG, vhost_user_iotlb_msg, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_CONFIG, vhost_user_get_config, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_CONFIG, vhost_user_set_config, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_ADVISE, 
vhost_user_set_postcopy_advise, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_LISTEN, 
vhost_user_set_postcopy_listen, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_END, vhost_user_postcopy_end, false) 
\
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_INFLIGHT_FD, vhost_user_get_inflight_fd, 
false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_INFLIGHT_FD, vhost_user_set_inflight_fd, 
true) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_SET_STATUS, vhost_user_set_status, false) \
-VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false)
-
-#define VHOST_MESSAGE_HANDLER(id, handler, accepts_fd) \
-       [id] = { #id, handler, accepts_fd },
+VHOST_MESSAGE_HANDLER(VHOST_USER_NONE, NULL, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_FEATURES, vhost_user_get_features, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_FEATURES, vhost_user_set_features, false, 
true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_OWNER, vhost_user_set_owner, false, true) 
\
+VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_OWNER, vhost_user_reset_owner, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_MEM_TABLE, vhost_user_set_mem_table, 
true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_BASE, vhost_user_set_log_base, true, 
true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_LOG_FD, vhost_user_set_log_fd, true, 
true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_NUM, vhost_user_set_vring_num, 
false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ADDR, vhost_user_set_vring_addr, 
false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_BASE, vhost_user_set_vring_base, 
false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_VRING_BASE, vhost_user_get_vring_base, 
false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_KICK, vhost_user_set_vring_kick, 
true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_CALL, vhost_user_set_vring_call, 
true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ERR, vhost_user_set_vring_err, 
true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_PROTOCOL_FEATURES, 
vhost_user_get_protocol_features, \
+       false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_PROTOCOL_FEATURES, 
vhost_user_set_protocol_features, \
+       false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_QUEUE_NUM, vhost_user_get_queue_num, 
false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_VRING_ENABLE, 
vhost_user_set_vring_enable, false, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SEND_RARP, vhost_user_send_rarp, false, true) 
\
+VHOST_MESSAGE_HANDLER(VHOST_USER_NET_SET_MTU, vhost_user_net_set_mtu, false, 
true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_BACKEND_REQ_FD, vhost_user_set_req_fd, 
true, true) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_IOTLB_MSG, vhost_user_iotlb_msg, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_CONFIG, vhost_user_get_config, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_CONFIG, vhost_user_set_config, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_ADVISE, 
vhost_user_set_postcopy_advise, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_LISTEN, 
vhost_user_set_postcopy_listen, false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_END, vhost_user_postcopy_end, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_INFLIGHT_FD, vhost_user_get_inflight_fd, 
false, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_INFLIGHT_FD, vhost_user_set_inflight_fd, 
true, false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_SET_STATUS, vhost_user_set_status, false, 
false) \
+VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false, 
false)
+
+#define VHOST_MESSAGE_HANDLER(id, handler, accepts_fd, lock_all_qps) \
+       [id] = { #id, handler, accepts_fd, lock_all_qps },
 static vhost_message_handler_t vhost_message_handlers[] = {
        VHOST_MESSAGE_HANDLERS
 };
@@ -3141,31 +3153,11 @@ vhost_user_msg_handler(int vid, int fd)
         * inactive, so it is safe. Otherwise taking the access_lock
         * would cause a dead lock.
         */
-       switch (request) {
-       case VHOST_USER_SET_FEATURES:
-       case VHOST_USER_SET_PROTOCOL_FEATURES:
-       case VHOST_USER_SET_OWNER:
-       case VHOST_USER_SET_MEM_TABLE:
-       case VHOST_USER_SET_LOG_BASE:
-       case VHOST_USER_SET_LOG_FD:
-       case VHOST_USER_SET_VRING_NUM:
-       case VHOST_USER_SET_VRING_ADDR:
-       case VHOST_USER_SET_VRING_BASE:
-       case VHOST_USER_SET_VRING_KICK:
-       case VHOST_USER_SET_VRING_CALL:
-       case VHOST_USER_SET_VRING_ERR:
-       case VHOST_USER_SET_VRING_ENABLE:
-       case VHOST_USER_SEND_RARP:
-       case VHOST_USER_NET_SET_MTU:
-       case VHOST_USER_SET_BACKEND_REQ_FD:
+       if (msg_handler->lock_all_qps) {
                if (!(dev->flags & VIRTIO_DEV_VDPA_CONFIGURED)) {
                        vhost_user_lock_all_queue_pairs(dev);
                        unlock_required = 1;
                }
-               break;
-       default:
-               break;
-
        }
 
        handled = false;
-- 
2.42.0

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