[PATCH v4 15/23] drm/msm: Protect ring->submits with it's own lock

Rob Clark
2020-10-23T16:52:03Z

One less place to rely on dev->struct_mutex.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
---
drivers/gpu/drm/msm/msm_gem_submit.c | 2 ++
drivers/gpu/drm/msm/msm_gpu.c | 37 ++++++++++++++++++++++------
drivers/gpu/drm/msm/msm_ringbuffer.c | 1 +
drivers/gpu/drm/msm/msm_ringbuffer.h | 6 +++++
4 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 044e9bee70a2..24ce4c65429d 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -65,7 +65,9 @@ void msm_gem_submit_free(struct msm_gem_submit *submit)
unsigned i;

dma_fence_put(submit->fence);
+ spin_lock(&submit->ring->submit_lock);
list_del(&submit->node);
+ spin_unlock(&submit->ring->submit_lock);
put_pid(submit->pid);
msm_submitqueue_put(submit->queue);

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 1667d8066897..1d6f3dc3fe78 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -270,6 +270,7 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
{
struct msm_gem_submit *submit;

+ spin_lock(&ring->submit_lock);
list_for_each_entry(submit, &ring->submits, node) {
if (submit->seqno > fence)
break;
@@ -277,6 +278,7 @@ static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
msm_update_fence(submit->ring->fctx,
submit->fence->seqno);
}
+ spin_unlock(&ring->submit_lock);
}

#ifdef CONFIG_DEV_COREDUMP
@@ -432,11 +434,14 @@ find_submit(struct msm_ringbuffer *ring, uint32_t fence)
{
struct msm_gem_submit *submit;

- WARN_ON(!mutex_is_locked(&ring->gpu->dev->struct_mutex));
-
- list_for_each_entry(submit, &ring->submits, node)
- if (submit->seqno == fence)
+ spin_lock(&ring->submit_lock);
+ list_for_each_entry(submit, &ring->submits, node) {
+ if (submit->seqno == fence) {
+ spin_unlock(&ring->submit_lock);
return submit;
+ }
+ }
+ spin_unlock(&ring->submit_lock);

return NULL;
}
@@ -533,8 +538,10 @@ static void recover_worker(struct work_struct *work)
for (i = 0; i < gpu->nr_rings; i++) {
struct msm_ringbuffer *ring = gpu->rb[i];

+ spin_lock(&ring->submit_lock);
list_for_each_entry(submit, &ring->submits, node)
gpu->funcs->submit(gpu, submit);
+ spin_unlock(&ring->submit_lock);
}
}

@@ -721,7 +728,6 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
static void retire_submits(struct msm_gpu *gpu)
{
struct drm_device *dev = gpu->dev;
- struct msm_gem_submit *submit, *tmp;
int i;

WARN_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -730,9 +736,24 @@ static void retire_submits(struct msm_gpu *gpu)
for (i = 0; i < gpu->nr_rings; i++) {
struct msm_ringbuffer *ring = gpu->rb[i];

- list_for_each_entry_safe(submit, tmp, &ring->submits, node) {
- if (dma_fence_is_signaled(submit->fence))
+ while (true) {
+ struct msm_gem_submit *submit = NULL;
+
+ spin_lock(&ring->submit_lock);
+ submit = list_first_entry_or_null(&ring->submits,
+ struct msm_gem_submit, node);
+ spin_unlock(&ring->submit_lock);
+
+ /*
+ * If no submit, we are done. If submit->fence hasn't
+ * been signalled, then later submits are not signalled
+ * either, so we are also done.
+ */
+ if (submit && dma_fence_is_signaled(submit->fence)) {
retire_submit(gpu, ring, submit);
+ } else {
+ break;
+ }
}
}
}
@@ -775,7 +796,9 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)

submit->seqno = ++ring->seqno;

+ spin_lock(&ring->submit_lock);
list_add_tail(&submit->node, &ring->submits);
+ spin_unlock(&ring->submit_lock);

msm_rd_dump_submit(priv->rd, submit, NULL);

diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index 1b6958e908dc..4d2a2a4abef8 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -46,6 +46,7 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
ring->memptrs_iova = memptrs_iova;

INIT_LIST_HEAD(&ring->submits);
+ spin_lock_init(&ring->submit_lock);
spin_lock_init(&ring->preempt_lock);

snprintf(name, sizeof(name), "gpu-ring-%d", ring->id);
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 4956d1bc5d0e..fe55d4a1aa16 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -39,7 +39,13 @@ struct msm_ringbuffer {
int id;
struct drm_gem_object *bo;
uint32_t *start, *end, *cur, *next;
+
+ /*
+ * List of in-flight submits on this ring. Protected by submit_lock.
+ */
struct list_head submits;
+ spinlock_t submit_lock;
+
uint64_t iova;
uint32_t seqno;
uint32_t hangcheck_fence;
--
2.26.2