Re: [Qemu-devel] [PATCH 02/10] hw/rdma: Introduce locked qlist

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

Hi Yuval,

On 1/31/19 3:08 PM, Yuval Shaia wrote:
> To make code more readable move handling of locked list to a generic
> functions.
>
> Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
> ---
>   hw/rdma/rdma_backend.c      | 20 +++++--------------
>   hw/rdma/rdma_backend_defs.h |  8 ++------
>   hw/rdma/rdma_utils.c        | 39 +++++++++++++++++++++++++++++++++++++
>   hw/rdma/rdma_utils.h        |  9 +++++++++
>   4 files changed, 55 insertions(+), 21 deletions(-)
>
> diff --git a/hw/rdma/rdma_backend.c b/hw/rdma/rdma_backend.c
> index 5f60856d19..2f6372f8f0 100644
> --- a/hw/rdma/rdma_backend.c
> +++ b/hw/rdma/rdma_backend.c
> @@ -527,9 +527,7 @@ static unsigned int save_mad_recv_buffer(RdmaBackendDev *backend_dev,
>       bctx->up_ctx = ctx;
>       bctx->sge = *sge;
>   
> -    qemu_mutex_lock(&backend_dev->recv_mads_list.lock);
> -    qlist_append_int(backend_dev->recv_mads_list.list, bctx_id);
> -    qemu_mutex_unlock(&backend_dev->recv_mads_list.lock);
> +    rdma_locked_list_append_int64(&backend_dev->recv_mads_list, bctx_id);
>   
>       return 0;
>   }
> @@ -913,23 +911,19 @@ static inline void build_mad_hdr(struct ibv_grh *grh, union ibv_gid *sgid,
>   static void process_incoming_mad_req(RdmaBackendDev *backend_dev,
>                                        RdmaCmMuxMsg *msg)
>   {
> -    QObject *o_ctx_id;
>       unsigned long cqe_ctx_id;
>       BackendCtx *bctx;
>       char *mad;
>   
>       trace_mad_message("recv", msg->umad.mad, msg->umad_len);
>   
> -    qemu_mutex_lock(&backend_dev->recv_mads_list.lock);
> -    o_ctx_id = qlist_pop(backend_dev->recv_mads_list.list);
> -    qemu_mutex_unlock(&backend_dev->recv_mads_list.lock);
> -    if (!o_ctx_id) {
> +    cqe_ctx_id = rdma_locked_list_pop_int64(&backend_dev->recv_mads_list);
> +    if (cqe_ctx_id == -ENOENT) {
>           rdma_warn_report("No more free MADs buffers, waiting for a while");
>           sleep(THR_POLL_TO);
>           return;
>       }
>   
> -    cqe_ctx_id = qnum_get_uint(qobject_to(QNum, o_ctx_id));
>       bctx = rdma_rm_get_cqe_ctx(backend_dev->rdma_dev_res, cqe_ctx_id);
>       if (unlikely(!bctx)) {
>           rdma_error_report("No matching ctx for req %ld", cqe_ctx_id);
> @@ -994,8 +988,7 @@ static int mad_init(RdmaBackendDev *backend_dev, CharBackend *mad_chr_be)
>           return -EIO;
>       }
>   
> -    qemu_mutex_init(&backend_dev->recv_mads_list.lock);
> -    backend_dev->recv_mads_list.list = qlist_new();
> +    rdma_locked_list_init(&backend_dev->recv_mads_list);
>   
>       enable_rdmacm_mux_async(backend_dev);
>   
> @@ -1010,10 +1003,7 @@ static void mad_fini(RdmaBackendDev *backend_dev)
>   {
>       disable_rdmacm_mux_async(backend_dev);
>       qemu_chr_fe_disconnect(backend_dev->rdmacm_mux.chr_be);
> -    if (backend_dev->recv_mads_list.list) {
> -        qlist_destroy_obj(QOBJECT(backend_dev->recv_mads_list.list));
> -        qemu_mutex_destroy(&backend_dev->recv_mads_list.lock);
> -    }
> +    rdma_locked_list_destroy(&backend_dev->recv_mads_list);
>   }
>   
>   int rdma_backend_get_gid_index(RdmaBackendDev *backend_dev,
> diff --git a/hw/rdma/rdma_backend_defs.h b/hw/rdma/rdma_backend_defs.h
> index 15ae8b970e..bec0457f25 100644
> --- a/hw/rdma/rdma_backend_defs.h
> +++ b/hw/rdma/rdma_backend_defs.h
> @@ -20,6 +20,7 @@
>   #include "chardev/char-fe.h"
>   #include <infiniband/verbs.h>
>   #include "contrib/rdmacm-mux/rdmacm-mux.h"
> +#include "rdma_utils.h"
>   
>   typedef struct RdmaDeviceResources RdmaDeviceResources;
>   
> @@ -30,11 +31,6 @@ typedef struct RdmaBackendThread {
>       bool is_running; /* Set by the thread to report its status */
>   } RdmaBackendThread;
>   
> -typedef struct RecvMadList {
> -    QemuMutex lock;
> -    QList *list;
> -} RecvMadList;
> -
>   typedef struct RdmaCmMux {
>       CharBackend *chr_be;
>       int can_receive;
> @@ -48,7 +44,7 @@ typedef struct RdmaBackendDev {
>       struct ibv_context *context;
>       struct ibv_comp_channel *channel;
>       uint8_t port_num;
> -    RecvMadList recv_mads_list;
> +    LockedList recv_mads_list;
>       RdmaCmMux rdmacm_mux;
>   } RdmaBackendDev;
>   
> diff --git a/hw/rdma/rdma_utils.c b/hw/rdma/rdma_utils.c
> index f1c980c6be..a2a4ea2a15 100644
> --- a/hw/rdma/rdma_utils.c
> +++ b/hw/rdma/rdma_utils.c
> @@ -14,6 +14,8 @@
>    */
>   
>   #include "qemu/osdep.h"
> +#include "qapi/qmp/qlist.h"
> +#include "qapi/qmp/qnum.h"
>   #include "trace.h"
>   #include "rdma_utils.h"
>   
> @@ -55,3 +57,40 @@ void rdma_pci_dma_unmap(PCIDevice *dev, void *buffer, dma_addr_t len)
>           pci_dma_unmap(dev, buffer, len, DMA_DIRECTION_TO_DEVICE, 0);
>       }
>   }
> +
> +void rdma_locked_list_init(LockedList *list)
> +{
> +    qemu_mutex_init(&list->lock);
> +    list->list = qlist_new();
> +}
> +
> +void rdma_locked_list_destroy(LockedList *list)
> +{
> +    if (list->list) {
> +        qlist_destroy_obj(QOBJECT(list->list));
> +        qemu_mutex_destroy(&list->lock);
> +        list->list = NULL;
> +    }
> +}
> +
> +void rdma_locked_list_append_int64(LockedList *list, int64_t value)
> +{
> +    qemu_mutex_lock(&list->lock);
> +    qlist_append_int(list->list, value);
> +    qemu_mutex_unlock(&list->lock);
> +}
> +
> +int64_t rdma_locked_list_pop_int64(LockedList *list)
> +{
> +    QObject *obj;
> +
> +    qemu_mutex_lock(&list->lock);
> +    obj = qlist_pop(list->list);
> +    qemu_mutex_unlock(&list->lock);
> +
> +    if (!obj) {
> +        return -ENOENT;
> +    }
> +
> +    return qnum_get_uint(qobject_to(QNum, obj));
> +}
> diff --git a/hw/rdma/rdma_utils.h b/hw/rdma/rdma_utils.h
> index acd148837f..4ba9956f81 100644
> --- a/hw/rdma/rdma_utils.h
> +++ b/hw/rdma/rdma_utils.h
> @@ -29,8 +29,17 @@
>   #define rdma_info_report(fmt, ...) \
>       info_report("%s: " fmt, "rdma", ## __VA_ARGS__)
>   
> +typedef struct LockedList {

The naming is a little off, maybe SynchronizedList ?

The more pressing issue, it doesn't seem this code is related to RDMA.
Does anybody think we should move this code to more appropriate place?

Thanks,
Marcel

> +    QemuMutex lock;
> +    QList *list;
> +} LockedList;




> +
>   void *rdma_pci_dma_map(PCIDevice *dev, dma_addr_t addr, dma_addr_t plen);
>   void rdma_pci_dma_unmap(PCIDevice *dev, void *buffer, dma_addr_t len);
> +void rdma_locked_list_init(LockedList *list);
> +void rdma_locked_list_destroy(LockedList *list);
> +void rdma_locked_list_append_int64(LockedList *list, int64_t value);
> +int64_t rdma_locked_list_pop_int64(LockedList *list);
>   
>   static inline void addrconf_addr_eui48(uint8_t *eui, const char *addr)
>   {