Re: [PATCH v2] lockable: Replace locks with lock guard macros

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

Hi Simran,

On 4/2/20 9:50 AM, Simran Singhal wrote:
> Replace manual lock()/unlock() calls with lock guard macros
> (QEMU_LOCK_GUARD/WITH_QEMU_LOCK_GUARD).
>
> Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
> ---
> Changes in v2:
>          -Drop changes in file hw/rdma/rdma_utils.c
>
>   hw/hyperv/hyperv.c     | 15 ++++++-------
>   hw/rdma/rdma_backend.c | 50 +++++++++++++++++++++---------------------
>   hw/rdma/rdma_rm.c      |  3 +--
>   3 files changed, 33 insertions(+), 35 deletions(-)
>
> diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c
> index 8ca3706f5b..4ddafe1de1 100644
> --- a/hw/hyperv/hyperv.c
> +++ b/hw/hyperv/hyperv.c
> @@ -15,6 +15,7 @@
>   #include "sysemu/kvm.h"
>   #include "qemu/bitops.h"
>   #include "qemu/error-report.h"
> +#include "qemu/lockable.h"
>   #include "qemu/queue.h"
>   #include "qemu/rcu.h"
>   #include "qemu/rcu_queue.h"
> @@ -491,7 +492,7 @@ int hyperv_set_msg_handler(uint32_t conn_id, HvMsgHandler handler, void *data)
>       int ret;
>       MsgHandler *mh;
>   
> -    qemu_mutex_lock(&handlers_mutex);
> +    QEMU_LOCK_GUARD(&handlers_mutex);

It does not passes compilation:
     export ARCH=x86_64
     make docker-image-fedora V=1 NETWORK=1
     make docker-test-debug@fedora TARGET_LIST=x86_64-softmmu NETWORK=1

Error:

  CC      x86_64-softmmu/hw/net/virtio-net.o
/tmp/qemu-test/src/hw/hyperv/hyperv.c:495:5: error: unused variable 
'qemu_lockable_auto__COUNTER__' [-Werror,-Wunused-variable]
     QEMU_LOCK_GUARD(&handlers_mutex);
     ^
/tmp/qemu-test/src/include/qemu/lockable.h:173:29: note: expanded from 
macro 'QEMU_LOCK_GUARD'
     g_autoptr(QemuLockable) qemu_lockable_auto##__COUNTER__ = \
                             ^
<scratch space>:24:1: note: expanded from here
qemu_lockable_auto__COUNTER__
^
/tmp/qemu-test/src/hw/hyperv/hyperv.c:568:5: error: unused variable 
'qemu_lockable_auto__COUNTER__' [-Werror,-Wunused-variable]
     QEMU_LOCK_GUARD(&handlers_mutex);
     ^
/tmp/qemu-test/src/include/qemu/lockable.h:173:29: note: expanded from 
macro 'QEMU_LOCK_GUARD'
     g_autoptr(QemuLockable) qemu_lockable_auto##__COUNTER__ = \
                             ^
<scratch space>:39:1: note: expanded from here
qemu_lockable_auto__COUNTER__
^
2 errors generated.

I suggest splitting it into an pvrdma path and hyperv patch anyway.
It will be nice to get an ack from the hyperv maintainer, adding Roman.

Thanks,
Marcel


>       QLIST_FOREACH(mh, &msg_handlers, link) {
>           if (mh->conn_id == conn_id) {
>               if (handler) {
> @@ -501,7 +502,7 @@ int hyperv_set_msg_handler(uint32_t conn_id, HvMsgHandler handler, void *data)
>                   g_free_rcu(mh, rcu);
>                   ret = 0;
>               }
> -            goto unlock;
> +            return ret;
>           }
>       }
>   
> @@ -515,8 +516,7 @@ int hyperv_set_msg_handler(uint32_t conn_id, HvMsgHandler handler, void *data)
>       } else {
>           ret = -ENOENT;
>       }
> -unlock:
> -    qemu_mutex_unlock(&handlers_mutex);
> +
>       return ret;
>   }
>   
> @@ -565,7 +565,7 @@ static int set_event_flag_handler(uint32_t conn_id, EventNotifier *notifier)
>       int ret;
>       EventFlagHandler *handler;
>   
> -    qemu_mutex_lock(&handlers_mutex);
> +    QEMU_LOCK_GUARD(&handlers_mutex);
>       QLIST_FOREACH(handler, &event_flag_handlers, link) {
>           if (handler->conn_id == conn_id) {
>               if (notifier) {
> @@ -575,7 +575,7 @@ static int set_event_flag_handler(uint32_t conn_id, EventNotifier *notifier)
>                   g_free_rcu(handler, rcu);
>                   ret = 0;
>               }
> -            goto unlock;
> +            return ret;
>           }
>       }
>   
> @@ -588,8 +588,7 @@ static int set_event_flag_handler(uint32_t conn_id, EventNotifier *notifier)
>       } else {
>           ret = -ENOENT;
>       }
> -unlock:
> -    qemu_mutex_unlock(&handlers_mutex);
> +
>       return ret;
>   }
>   
> diff --git a/hw/rdma/rdma_backend.c b/hw/rdma/rdma_backend.c
> index 3dd39fe1a7..db7e5c8be5 100644
> --- a/hw/rdma/rdma_backend.c
> +++ b/hw/rdma/rdma_backend.c
> @@ -95,36 +95,36 @@ static int rdma_poll_cq(RdmaDeviceResources *rdma_dev_res, struct ibv_cq *ibcq)
>       struct ibv_wc wc[2];
>       RdmaProtectedGSList *cqe_ctx_list;
>   
> -    qemu_mutex_lock(&rdma_dev_res->lock);
> -    do {
> -        ne = ibv_poll_cq(ibcq, ARRAY_SIZE(wc), wc);
> +    WITH_QEMU_LOCK_GUARD(&rdma_dev_res->lock) {
> +        do {
> +            ne = ibv_poll_cq(ibcq, ARRAY_SIZE(wc), wc);
>   
> -        trace_rdma_poll_cq(ne, ibcq);
> +            trace_rdma_poll_cq(ne, ibcq);
>   
> -        for (i = 0; i < ne; i++) {
> -            bctx = rdma_rm_get_cqe_ctx(rdma_dev_res, wc[i].wr_id);
> -            if (unlikely(!bctx)) {
> -                rdma_error_report("No matching ctx for req %"PRId64,
> -                                  wc[i].wr_id);
> -                continue;
> -            }
> +            for (i = 0; i < ne; i++) {
> +                bctx = rdma_rm_get_cqe_ctx(rdma_dev_res, wc[i].wr_id);
> +                if (unlikely(!bctx)) {
> +                    rdma_error_report("No matching ctx for req %"PRId64,
> +                                      wc[i].wr_id);
> +                    continue;
> +                }
>   
> -            comp_handler(bctx->up_ctx, &wc[i]);
> +                comp_handler(bctx->up_ctx, &wc[i]);
>   
> -            if (bctx->backend_qp) {
> -                cqe_ctx_list = &bctx->backend_qp->cqe_ctx_list;
> -            } else {
> -                cqe_ctx_list = &bctx->backend_srq->cqe_ctx_list;
> -            }
> +                if (bctx->backend_qp) {
> +                    cqe_ctx_list = &bctx->backend_qp->cqe_ctx_list;
> +                } else {
> +                    cqe_ctx_list = &bctx->backend_srq->cqe_ctx_list;
> +                }
>   
> -            rdma_protected_gslist_remove_int32(cqe_ctx_list, wc[i].wr_id);
> -            rdma_rm_dealloc_cqe_ctx(rdma_dev_res, wc[i].wr_id);
> -            g_free(bctx);
> -        }
> -        total_ne += ne;
> -    } while (ne > 0);
> -    atomic_sub(&rdma_dev_res->stats.missing_cqe, total_ne);
> -    qemu_mutex_unlock(&rdma_dev_res->lock);
> +                rdma_protected_gslist_remove_int32(cqe_ctx_list, wc[i].wr_id);
> +                rdma_rm_dealloc_cqe_ctx(rdma_dev_res, wc[i].wr_id);
> +                g_free(bctx);
> +            }
> +            total_ne += ne;
> +        } while (ne > 0);
> +        atomic_sub(&rdma_dev_res->stats.missing_cqe, total_ne);
> +    }
>   
>       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 7e9ea283c9..60957f88db 100644
> --- a/hw/rdma/rdma_rm.c
> +++ b/hw/rdma/rdma_rm.c
> @@ -147,14 +147,13 @@ static inline void rdma_res_tbl_dealloc(RdmaRmResTbl *tbl, uint32_t handle)
>   {
>       trace_rdma_res_tbl_dealloc(tbl->name, handle);
>   
> -    qemu_mutex_lock(&tbl->lock);
> +    QEMU_LOCK_GUARD(&tbl->lock);
>   
>       if (handle < tbl->tbl_sz) {
>           clear_bit(handle, tbl->bitmap);
>           tbl->used--;
>       }
>   
> -    qemu_mutex_unlock(&tbl->lock);
>   }
>   
>   int rdma_rm_alloc_pd(RdmaDeviceResources *dev_res, RdmaBackendDev *backend_dev,