Re: [Qemu-devel] [PATCH 04/10] hw/rdma: Protect against concurrent execution of poll_cq

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

On 1/31/19 3:08 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 <yuval.shaia@oracle.com>
> ---
>   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 b7d6afb5da..bf8e889144 100644
> --- a/hw/rdma/rdma_backend.c
> +++ b/hw/rdma/rdma_backend.c
> @@ -70,6 +70,7 @@ static int 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);
>   
> @@ -90,6 +91,7 @@ static int 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 1ba77ac42c..9408bfb751 100644
> --- a/hw/rdma/rdma_rm.c
> +++ b/hw/rdma/rdma_rm.c
> @@ -619,12 +619,16 @@ 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 08692e87d4..9e98565a28 100644
> --- a/hw/rdma/rdma_rm_defs.h
> +++ b/hw/rdma/rdma_rm_defs.h
> @@ -109,6 +109,7 @@ 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: Marcel Apfelbaum<marcel.apfelbaum@gmail.com>

Thanks,
Marcel