[PATCH v2 2/2] drm/amdgpu: Move old fence waiting before reservation lock is aquired.
Chunming Zhou
zhoucm1 at amd.com
Wed Oct 11 07:41:44 UTC 2017
After ctx mutex is added, pthread_mutext in libdrm can be removed now.
David Zhou
On 2017年10月11日 15:25, Christian König wrote:
> Yes, the mutex is mandatory.
>
> As I explained before it doesn't matter what userspace is doing, the
> kernel IOCTL must always be thread safe.
>
> Otherwise userspace could force the kernel to run into a BUG_ON() or
> worse.
>
> Additional to that we already use an CS interface upstream which
> doesn't have a pthread_mutex any more.
>
> Regards,
> Christian.
>
> Am 11.10.2017 um 05:28 schrieb Liu, Monk:
>> Hi Andrey & Christian
>>
>> Do we really need the mutext lock here?
>> Libdrm_amdgpu already has the pthread_mutext to protect multi-thread
>> racing issues, kernel side should be safe with that
>>
>> BR Monk
>>
>> -----Original Message-----
>> From: Andrey Grodzovsky [mailto:andrey.grodzovsky at amd.com]
>> Sent: Wednesday, October 11, 2017 4:50 AM
>> To: Koenig, Christian <Christian.Koenig at amd.com>; Liu, Monk
>> <Monk.Liu at amd.com>; amd-gfx at lists.freedesktop.org
>> Cc: Grodzovsky, Andrey <Andrey.Grodzovsky at amd.com>
>> Subject: [PATCH v2 2/2] drm/amdgpu: Move old fence waiting before
>> reservation lock is aquired.
>>
>> Helps avoiding deadlock during GPU reset.
>> Added mutex to amdgpu_ctx to preserve order of fences on a ring.
>>
>> v2:
>> Put waiting logic in a function in a seperate function in amdgpu_ctx.c
>>
>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 4 ++++
>> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 8 ++++++--
>> drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 30
>> ++++++++++++++++++++++++------
>> 3 files changed, 34 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> index da48f97..235eca5 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> @@ -741,6 +741,7 @@ struct amdgpu_ctx {
>> bool preamble_presented;
>> enum amd_sched_priority init_priority;
>> enum amd_sched_priority override_priority;
>> + struct mutex lock;
>> };
>> struct amdgpu_ctx_mgr {
>> @@ -763,9 +764,12 @@ void amdgpu_ctx_priority_override(struct
>> amdgpu_ctx *ctx, int amdgpu_ctx_ioctl(struct drm_device *dev, void
>> *data,
>> struct drm_file *filp);
>> +int amdgpu_ctx_wait_prev_fence(struct amdgpu_ctx *ctx, unsigned
>> +ring_id);
>> +
>> void amdgpu_ctx_mgr_init(struct amdgpu_ctx_mgr *mgr); void
>> amdgpu_ctx_mgr_fini(struct amdgpu_ctx_mgr *mgr);
>> +
>> /*
>> * file private structure
>> */
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index 1a54e53..c36297c 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -90,6 +90,8 @@ static int amdgpu_cs_parser_init(struct
>> amdgpu_cs_parser *p, void *data)
>> goto free_chunk;
>> }
>> + mutex_lock(&p->ctx->lock);
>> +
>> /* get chunks */
>> chunk_array_user = u64_to_user_ptr(cs->in.chunks);
>> if (copy_from_user(chunk_array, chunk_array_user, @@ -737,8
>> +739,10 @@ static void amdgpu_cs_parser_fini(struct amdgpu_cs_parser
>> *parser, int error,
>> dma_fence_put(parser->fence);
>> - if (parser->ctx)
>> + if (parser->ctx) {
>> + mutex_unlock(&parser->ctx->lock);
>> amdgpu_ctx_put(parser->ctx);
>> + }
>> if (parser->bo_list)
>> amdgpu_bo_list_put(parser->bo_list);
>> @@ -992,7 +996,7 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device
>> *adev,
>> parser->job->ring->funcs->type == AMDGPU_RING_TYPE_VCE))
>> return -EINVAL;
>> - return 0;
>> + return amdgpu_ctx_wait_prev_fence(parser->ctx,
>> +parser->job->ring->idx);
>> }
>> static int amdgpu_cs_process_fence_dep(struct amdgpu_cs_parser
>> *p, diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> index a78b03f6..4309820 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
>> @@ -67,6 +67,8 @@ static int amdgpu_ctx_init(struct amdgpu_device *adev,
>> if (!ctx->fences)
>> return -ENOMEM;
>> + mutex_init(&ctx->lock);
>> +
>> for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
>> ctx->rings[i].sequence = 1;
>> ctx->rings[i].fences = &ctx->fences[amdgpu_sched_jobs * i];
>> @@ -126,6 +128,8 @@ static void amdgpu_ctx_fini(struct amdgpu_ctx *ctx)
>> &ctx->rings[i].entity);
>> amdgpu_queue_mgr_fini(adev, &ctx->queue_mgr);
>> +
>> + mutex_destroy(&ctx->lock);
>> }
>> static int amdgpu_ctx_alloc(struct amdgpu_device *adev, @@
>> -296,12 +300,8 @@ int amdgpu_ctx_add_fence(struct amdgpu_ctx *ctx,
>> struct amdgpu_ring *ring,
>> idx = seq & (amdgpu_sched_jobs - 1);
>> other = cring->fences[idx];
>> - if (other) {
>> - signed long r;
>> - r = dma_fence_wait_timeout(other, true, MAX_SCHEDULE_TIMEOUT);
>> - if (r < 0)
>> - return r;
>> - }
>> + if (other)
>> + BUG_ON(!dma_fence_is_signaled(other));
>> dma_fence_get(fence);
>> @@ -372,6 +372,24 @@ void amdgpu_ctx_priority_override(struct
>> amdgpu_ctx *ctx,
>> }
>> }
>> +int amdgpu_ctx_wait_prev_fence(struct amdgpu_ctx *ctx, unsigned
>> +ring_id) {
>> + struct amdgpu_ctx_ring *cring = &ctx->rings[ring_id];
>> + unsigned idx = cring->sequence & (amdgpu_sched_jobs - 1);
>> + struct dma_fence *other = cring->fences[idx];
>> +
>> + if (other) {
>> + signed long r;
>> + r = dma_fence_wait_timeout(other, false, MAX_SCHEDULE_TIMEOUT);
>> + if (r < 0) {
>> + DRM_ERROR("Error (%ld) waiting for fence!\n", r);
>> + return r;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> void amdgpu_ctx_mgr_init(struct amdgpu_ctx_mgr *mgr) {
>> mutex_init(&mgr->lock);
>> --
>> 2.7.4
>>
>
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