[PATCH v2 7/8] vdpa_sim: replace the spinlock with a mutex to protect the state

Stefano Garzarella
2023-03-02T11:36:39Z

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>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
drivers/vdpa/vdpa_sim/vdpa_sim.h | 4 ++--
drivers/vdpa/vdpa_sim/vdpa_sim.c | 34 ++++++++++++++--------------
drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 4 ++--
drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 4 ++--
4 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
index ce83f9130a5d..4774292fba8c 100644
--- 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.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 6feb29726c2a..a28103a67ae7 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -166,7 +166,7 @@ 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 = &vdpasim->vdpa.dev;
@@ -275,13 +275,13 @@ 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)
@@ -299,9 +299,9 @@ 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;
}
@@ -398,9 +398,9 @@ 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;
}
@@ -409,19 +409,19 @@ 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;
}
@@ -430,9 +430,9 @@ 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;
}
@@ -442,7 +442,7 @@ 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) {
@@ -453,7 +453,7 @@ static int vdpasim_resume(struct vdpa_device *vdpa)
vdpasim->pending_kick = false;
}

- spin_unlock(&vdpasim->lock);
+ mutex_unlock(&vdpasim->mutex);

return 0;
}
@@ -525,14 +525,14 @@ 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_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index eb4897c8541e..568119e1553f 100644
--- 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 e61a9ecbfafe..7ab434592bfe 100644
--- 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;
--
2.39.2