Re: [Qemu-devel] [PATCH v6 03/11] hw/rdma: Protect against concurrent execution of poll_cq

[Kamal Heib]

On 3/11/19 12:29 PM, Yuval Shaia wrote:
> The function rdma_poll_cq is called from two contexts - completion
> handler thread which sense new completion on backend channel and
> explicitly as result of guest issuing poll_cq command.
> 
> Add lock to protect against concurrent executions.
> 
> Signed-off-by: Yuval Shaia <address@hidden>
> Reviewed-by: Marcel Apfelbaum <address@hidden>
> ---
>  hw/rdma/rdma_backend.c | 2 ++
>  hw/rdma/rdma_rm.c      | 4 ++++
>  hw/rdma/rdma_rm_defs.h | 1 +
>  3 files changed, 7 insertions(+)
> 
> diff --git a/hw/rdma/rdma_backend.c b/hw/rdma/rdma_backend.c
> index 37edf42..1897540 100644
> --- a/hw/rdma/rdma_backend.c
> +++ b/hw/rdma/rdma_backend.c
> @@ -70,6 +70,7 @@ static void rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, 
> struct ibv_cq *ibcq)
>      BackendCtx *bctx;
>      struct ibv_wc wc[2];
>  
> +    qemu_mutex_lock(&rdma_dev_res->lock);
>      do {
>          ne = ibv_poll_cq(ibcq, ARRAY_SIZE(wc), wc);
>  
> @@ -89,6 +90,7 @@ static void rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, 
> struct ibv_cq *ibcq)
>              g_free(bctx);
>          }
>      } while (ne > 0);
> +    qemu_mutex_unlock(&rdma_dev_res->lock);
>  
>      if (ne < 0) {
>          rdma_error_report("ibv_poll_cq fail, rc=%d, errno=%d", ne, errno);
> diff --git a/hw/rdma/rdma_rm.c b/hw/rdma/rdma_rm.c
> index 66177b4..7ea62a9 100644
> --- a/hw/rdma/rdma_rm.c
> +++ b/hw/rdma/rdma_rm.c
> @@ -617,12 +617,16 @@ int rdma_rm_init(RdmaDeviceResources *dev_res, struct 
> ibv_device_attr *dev_attr)
>  
>      init_ports(dev_res);
>  
> +    qemu_mutex_init(&dev_res->lock);
> +
>      return 0;
>  }
>  
>  void rdma_rm_fini(RdmaDeviceResources *dev_res, RdmaBackendDev *backend_dev,
>                    const char *ifname)
>  {
> +    qemu_mutex_destroy(&dev_res->lock);
> +
>      fini_ports(dev_res, backend_dev, ifname);
>  
>      res_tbl_free(&dev_res->uc_tbl);
> diff --git a/hw/rdma/rdma_rm_defs.h b/hw/rdma/rdma_rm_defs.h
> index 0ba61d1..f0ee1f3 100644
> --- a/hw/rdma/rdma_rm_defs.h
> +++ b/hw/rdma/rdma_rm_defs.h
> @@ -105,6 +105,7 @@ typedef struct RdmaDeviceResources {
>      RdmaRmResTbl cq_tbl;
>      RdmaRmResTbl cqe_ctx_tbl;
>      GHashTable *qp_hash; /* Keeps mapping between real and emulated */
> +    QemuMutex lock;
>  } RdmaDeviceResources;
>  
>  #endif
> 

Reviewed-by: Kamal Heib <address@hidden>