vdpa_sim: replace the spinlock with a mutex to protect the state

The spinlock we use to protect the state of the simulator is sometimes
held for a long time (for example, when devices handle requests).

This also prevents us from calling functions that might sleep (such as
kthread_flush_work() in the next patch), and thus having to release
and retake the lock.

For these reasons, let's replace the spinlock with a mutex that gives
us more flexibility.

Suggested-by: Jason Wang <jasowang@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20230404131730.45920-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index bd9f905..2b2e439 100644 (file)
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -178,7 +178,7 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
        if (IS_ERR(vdpasim->worker))
                goto err_iommu;
 
-       spin_lock_init(&vdpasim->lock);
+       mutex_init(&vdpasim->mutex);
        spin_lock_init(&vdpasim->iommu_lock);
 
        dev->dma_mask = &dev->coherent_dma_mask;
@@ -286,13 +286,13 @@ static void vdpasim_set_vq_ready(struct vdpa_device *vdpa, u16 idx, bool ready)
        struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
        bool old_ready;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        old_ready = vq->ready;
        vq->ready = ready;
        if (vq->ready && !old_ready) {
                vdpasim_queue_ready(vdpasim, idx);
        }
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 }
 
 static bool vdpasim_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
@@ -310,9 +310,9 @@ static int vdpasim_set_vq_state(struct vdpa_device *vdpa, u16 idx,
        struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
        struct vringh *vrh = &vq->vring;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        vrh->last_avail_idx = state->split.avail_index;
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }
@@ -409,9 +409,9 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
        u8 status;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        status = vdpasim->status;
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return status;
 }
@@ -420,19 +420,19 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
 {
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        vdpasim->status = status;
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 }
 
 static int vdpasim_reset(struct vdpa_device *vdpa)
 {
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        vdpasim->status = 0;
        vdpasim_do_reset(vdpasim);
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }
@@ -441,9 +441,9 @@ static int vdpasim_suspend(struct vdpa_device *vdpa)
 {
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        vdpasim->running = false;
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }
@@ -453,7 +453,7 @@ static int vdpasim_resume(struct vdpa_device *vdpa)
        struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
        int i;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
        vdpasim->running = true;
 
        if (vdpasim->pending_kick) {
@@ -464,7 +464,7 @@ static int vdpasim_resume(struct vdpa_device *vdpa)
                vdpasim->pending_kick = false;
        }
 
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }
@@ -536,14 +536,14 @@ static int vdpasim_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
 
        iommu = &vdpasim->iommu[asid];
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
 
        for (i = 0; i < vdpasim->dev_attr.nvqs; i++)
                if (vdpasim_get_vq_group(vdpa, i) == group)
                        vringh_set_iotlb(&vdpasim->vqs[i].vring, iommu,
                                         &vdpasim->iommu_lock);
 
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        return 0;
 }

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
index ce83f91..4774292 100644 (file)
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
@@ -60,8 +60,8 @@ struct vdpasim {
        struct kthread_worker *worker;
        struct kthread_work work;
        struct vdpasim_dev_attr dev_attr;
-       /* spinlock to synchronize virtqueue state */
-       spinlock_t lock;
+       /* mutex to synchronize virtqueue state */
+       struct mutex mutex;
        /* virtio config according to device type */
        void *config;
        struct vhost_iotlb *iommu;

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index eb4897c..568119e 100644 (file)
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -290,7 +290,7 @@ static void vdpasim_blk_work(struct vdpasim *vdpasim)
        bool reschedule = false;
        int i;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
 
        if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
                goto out;
@@ -321,7 +321,7 @@ static void vdpasim_blk_work(struct vdpasim *vdpasim)
                }
        }
 out:
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        if (reschedule)
                vdpasim_schedule_work(vdpasim);

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
index 30ac41c..5592050 100644 (file)
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
@@ -201,7 +201,7 @@ static void vdpasim_net_work(struct vdpasim *vdpasim)
        u64 rx_drops = 0, rx_overruns = 0, rx_errors = 0, tx_errors = 0;
        int err;
 
-       spin_lock(&vdpasim->lock);
+       mutex_lock(&vdpasim->mutex);
 
        if (!vdpasim->running)
                goto out;
@@ -264,7 +264,7 @@ static void vdpasim_net_work(struct vdpasim *vdpasim)
        }
 
 out:
-       spin_unlock(&vdpasim->lock);
+       mutex_unlock(&vdpasim->mutex);
 
        u64_stats_update_begin(&net->tx_stats.syncp);
        net->tx_stats.pkts += tx_pkts;