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winsys/amdgpu: fix a deadlock when waiting for submission_in_progress 

First this happens:

1) amdgpu_cs_flush (lock bo_fence_lock)
   -> amdgpu_add_fence_dependency
   -> os_wait_until_zero (wait for submission_in_progress) - WAITING

2) amdgpu_bo_create
   -> pb_cache_reclaim_buffer (lock pb_cache::mutex)
   -> pb_cache_is_buffer_compat
   -> amdgpu_bo_wait (lock bo_fence_lock) - WAITING

So both bo_fence_lock and pb_cache::mutex are held. amdgpu_bo_create can't
continue. amdgpu_cs_flush is waiting for the CS ioctl to finish the job,
but the CS ioctl is trying to release a buffer:

3) amdgpu_cs_submit_ib (CS thread - job entrypoint)
   -> amdgpu_cs_context_cleanup
   -> pb_reference
   -> pb_destroy
   -> amdgpu_bo_destroy_or_cache
   -> pb_cache_add_buffer (lock pb_cache::mutex) - DEADLOCK

The simple solution is not to wait for submission_in_progress, which we
need in order to create the list of dependencies for the CS ioctl. Instead
of building the list of dependencies as a direct input to the CS ioctl,
build the list of dependencies as a list of fences, and make the final list
of dependencies in the CS thread itself.

Therefore, amdgpu_cs_flush doesn't have to wait and can continue.
Then, amdgpu_bo_create can continue and return. And then amdgpu_cs_submit_ib
can continue.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101294

Cc: 17.1 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
This commit is contained in:
Marek Olšák 2017-06-19 19:39:05 +02:00
parent afeaa2e98a
commit 58af1f6bb0
2 changed files with 42 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/gallium/winsys/amdgpu/drm/amdgpu_cs.c
View File

@ -752,10 +752,13 @@ static void amdgpu_cs_context_cleanup(struct amdgpu_cs_context *cs)
p_atomic_dec(&cs->sparse_buffers[i].bo->num_cs_references);
amdgpu_winsys_bo_reference(&cs->sparse_buffers[i].bo, NULL);
}
for (i = 0; i < cs->num_fence_dependencies; i++)
amdgpu_fence_reference(&cs->fence_dependencies[i], NULL);
cs->num_real_buffers = 0;
cs->num_slab_buffers = 0;
cs->num_sparse_buffers = 0;
cs->num_fence_dependencies = 0;
amdgpu_fence_reference(&cs->fence, NULL);
memset(cs->buffer_indices_hashlist, -1, sizeof(cs->buffer_indices_hashlist));
@ -770,7 +773,7 @@ static void amdgpu_destroy_cs_context(struct amdgpu_cs_context *cs)
FREE(cs->handles);
FREE(cs->slab_buffers);
FREE(cs->sparse_buffers);
FREE(cs->request.dependencies);
FREE(cs->fence_dependencies);
}
@ -981,7 +984,6 @@ static void amdgpu_add_fence_dependency(struct amdgpu_cs *acs,
{
struct amdgpu_cs_context *cs = acs->csc;
struct amdgpu_winsys_bo *bo = buffer->bo;
struct amdgpu_cs_fence *dep;
unsigned new_num_fences = 0;
for (unsigned j = 0; j < bo->num_fences; ++j) {
@ -1003,21 +1005,21 @@ static void amdgpu_add_fence_dependency(struct amdgpu_cs *acs,
if (!(buffer->usage & RADEON_USAGE_SYNCHRONIZED))
continue;
if (bo_fence->submission_in_progress)
os_wait_until_zero(&bo_fence->submission_in_progress,
PIPE_TIMEOUT_INFINITE);
idx = cs->request.number_of_dependencies++;
if (idx >= cs->max_dependencies) {
idx = cs->num_fence_dependencies++;
if (idx >= cs->max_fence_dependencies) {
unsigned size;
const unsigned increment = 8;
cs->max_dependencies = idx + 8;
size = cs->max_dependencies * sizeof(struct amdgpu_cs_fence);
cs->request.dependencies = realloc(cs->request.dependencies, size);
cs->max_fence_dependencies = idx + increment;
size = cs->max_fence_dependencies * sizeof(cs->fence_dependencies[0]);
cs->fence_dependencies = realloc(cs->fence_dependencies, size);
/* Clear the newly-allocated elements. */
memset(cs->fence_dependencies + idx, 0,
increment * sizeof(cs->fence_dependencies[0]));
}
dep = &cs->request.dependencies[idx];
memcpy(dep, &bo_fence->fence, sizeof(*dep));
amdgpu_fence_reference(&cs->fence_dependencies[idx],
(struct pipe_fence_handle*)bo_fence);
}
for (unsigned j = new_num_fences; j < bo->num_fences; ++j)
@ -1088,7 +1090,7 @@ static void amdgpu_add_fence_dependencies(struct amdgpu_cs *acs)
{
struct amdgpu_cs_context *cs = acs->csc;
cs->request.number_of_dependencies = 0;
cs->num_fence_dependencies = 0;
amdgpu_add_fence_dependencies_list(acs, cs->fence, cs->num_real_buffers, cs->real_buffers);
amdgpu_add_fence_dependencies_list(acs, cs->fence, cs->num_slab_buffers, cs->slab_buffers);
@ -1136,7 +1138,30 @@ void amdgpu_cs_submit_ib(void *job, int thread_index)
struct amdgpu_winsys *ws = acs->ctx->ws;
struct amdgpu_cs_context *cs = acs->cst;
int i, r;
struct amdgpu_cs_fence *dependencies = NULL;
/* Set dependencies (input fences). */
if (cs->num_fence_dependencies) {
dependencies = alloca(sizeof(dependencies[0]) *
cs->num_fence_dependencies);
unsigned num = 0;
for (i = 0; i < cs->num_fence_dependencies; i++) {
struct amdgpu_fence *fence =
(struct amdgpu_fence*)cs->fence_dependencies[i];
/* Past fences can't be unsubmitted because we have only 1 CS thread. */
assert(!fence->submission_in_progress);
memcpy(&dependencies[num++], &fence->fence, sizeof(dependencies[0]));
}
cs->request.dependencies = dependencies;
cs->request.number_of_dependencies = num;
} else {
cs->request.dependencies = NULL;
cs->request.number_of_dependencies = 0;
}
/* Set the output fence. */
cs->request.fence_info.handle = NULL;
if (amdgpu_cs_has_user_fence(cs)) {
cs->request.fence_info.handle = acs->ctx->user_fence_bo;

4
src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
View File

@ -105,7 +105,9 @@ struct amdgpu_cs_context {
unsigned last_added_bo_usage;
uint64_t last_added_bo_priority_usage;
unsigned max_dependencies;
struct pipe_fence_handle **fence_dependencies;
unsigned num_fence_dependencies;
unsigned max_fence_dependencies;
struct pipe_fence_handle *fence;