Re: [PATCH 4/4] amdgpu: use sync file for shared semaphores

[Daniel Vetter <daniel-/w4YWyX8dFk@public.gmane.org>]

On Tue, Mar 14, 2017 at 10:50:54AM +1000, Dave Airlie wrote:
> From: Dave Airlie <airlied@redhat.com>
> 
> This creates a new interface for amdgpu with ioctls to
> create/destroy/import and export shared semaphores using
> sem object backed by the sync_file code. The semaphores
> are not installed as fd (except for export), but rather
> like other driver internal objects in an idr. The idr
> holds the initial reference on the sync file.
> 
> The command submission interface is enhanced with two new
> chunks, one for semaphore waiting, one for semaphore signalling
> and just takes a list of handles for each.
> 
> This is based on work originally done by David Zhou at AMD,
> with input from Christian Konig on what things should look like.
> 
> NOTE: this interface addition needs a version bump to expose
> it to userspace.
> 
> Signed-off-by: Dave Airlie <airlied@redhat.com>

Another uapi corner case: Since you allow semaphores to be created before
they have a first fence attached, that essentially creates future fences.
I.e. sync_file fd with no fence yet attached. We want that anyway, but
maybe not together with semaphores (since there's some more implications).

I think it'd be good to attach a dummy fence which already starts out as
signalled to sync_file->fence for semaphores. That way userspace can't go
evil, create a semaphore, then pass it to a driver which then promptly
oopses or worse because it assumes then when it has a sync_file, it also
has a fence. And the dummy fence could be globally shared, so not really
overhead.
-Daniel

> ---
>  drivers/gpu/drm/amd/amdgpu/Makefile     |   2 +-
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h     |  12 ++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c  |  70 ++++++++++-
>  drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c |   8 ++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_sem.c | 204 ++++++++++++++++++++++++++++++++
>  include/uapi/drm/amdgpu_drm.h           |  28 +++++
>  6 files changed, 322 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/gpu/drm/amd/amdgpu/amdgpu_sem.c
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/Makefile b/drivers/gpu/drm/amd/amdgpu/Makefile
> index 2814aad..404bcba 100644
> --- a/drivers/gpu/drm/amd/amdgpu/Makefile
> +++ b/drivers/gpu/drm/amd/amdgpu/Makefile
> @@ -24,7 +24,7 @@ amdgpu-y += amdgpu_device.o amdgpu_kms.o \
>  	atombios_encoders.o amdgpu_sa.o atombios_i2c.o \
>  	amdgpu_prime.o amdgpu_vm.o amdgpu_ib.o amdgpu_pll.o \
>  	amdgpu_ucode.o amdgpu_bo_list.o amdgpu_ctx.o amdgpu_sync.o \
> -	amdgpu_gtt_mgr.o amdgpu_vram_mgr.o amdgpu_virt.o
> +	amdgpu_gtt_mgr.o amdgpu_vram_mgr.o amdgpu_virt.o amdgpu_sem.o
>  
>  # add asic specific block
>  amdgpu-$(CONFIG_DRM_AMDGPU_CIK)+= cik.o cik_ih.o kv_smc.o kv_dpm.o \
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index c1b9135..4ed8811 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -702,6 +702,8 @@ struct amdgpu_fpriv {
>  	struct mutex		bo_list_lock;
>  	struct idr		bo_list_handles;
>  	struct amdgpu_ctx_mgr	ctx_mgr;
> +	spinlock_t		sem_handles_lock;
> +	struct idr		sem_handles;
>  };
>  
>  /*
> @@ -1814,5 +1816,15 @@ amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
>  		       uint64_t addr, struct amdgpu_bo **bo);
>  int amdgpu_cs_sysvm_access_required(struct amdgpu_cs_parser *parser);
>  
> +int amdgpu_sem_ioctl(struct drm_device *dev, void *data,
> +		     struct drm_file *filp);
> +void amdgpu_sem_destroy(struct amdgpu_fpriv *fpriv, u32 handle);
> +int amdgpu_sem_lookup_and_signal(struct amdgpu_fpriv *fpriv,
> +				 uint32_t handle,
> +				 struct dma_fence *fence);
> +int amdgpu_sem_lookup_and_sync(struct amdgpu_device *adev,
> +			       struct amdgpu_fpriv *fpriv,
> +			       struct amdgpu_sync *sync,
> +			       uint32_t handle);
>  #include "amdgpu_object.h"
>  #endif
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 4671432..80fc94b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -217,6 +217,8 @@ int amdgpu_cs_parser_init(struct amdgpu_cs_parser *p, void *data)
>  			break;
>  
>  		case AMDGPU_CHUNK_ID_DEPENDENCIES:
> +		case AMDGPU_CHUNK_ID_SEM_WAIT:
> +		case AMDGPU_CHUNK_ID_SEM_SIGNAL:
>  			break;
>  
>  		default:
> @@ -1009,6 +1011,28 @@ static int amdgpu_process_fence_dep(struct amdgpu_device *adev,
>  	return 0;
>  }
>  
> +static int amdgpu_process_sem_wait_dep(struct amdgpu_device *adev,
> +				       struct amdgpu_cs_parser *p,
> +				       struct amdgpu_cs_chunk *chunk)
> +{
> +	struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
> +	unsigned num_deps;
> +	int i, r;
> +	struct drm_amdgpu_cs_chunk_sem *deps;
> +
> +	deps = (struct drm_amdgpu_cs_chunk_sem *)chunk->kdata;
> +	num_deps = chunk->length_dw * 4 /
> +		sizeof(struct drm_amdgpu_cs_chunk_sem);
> +
> +	for (i = 0; i < num_deps; ++i) {
> +		r = amdgpu_sem_lookup_and_sync(adev, fpriv, &p->job->sync,
> +					       deps[i].handle);
> +		if (r)
> +			return r;
> +	}
> +	return 0;
> +}
> +
>  static int amdgpu_cs_dependencies(struct amdgpu_device *adev,
>  				  struct amdgpu_cs_parser *p)
>  {
> @@ -1023,12 +1047,56 @@ static int amdgpu_cs_dependencies(struct amdgpu_device *adev,
>  			r = amdgpu_process_fence_dep(adev, p, chunk);
>  			if (r)
>  				return r;
> +		} else if (chunk->chunk_id == AMDGPU_CHUNK_ID_SEM_WAIT) {
> +			r = amdgpu_process_sem_wait_dep(adev, p, chunk);
> +			if (r)
> +				return r;
>  		}
>  	}
>  
>  	return 0;
>  }
>  
> +static int amdgpu_process_sem_signal_dep(struct amdgpu_cs_parser *p,
> +					 struct amdgpu_cs_chunk *chunk,
> +					 struct dma_fence *fence)
> +{
> +	struct amdgpu_fpriv *fpriv = p->filp->driver_priv;
> +	unsigned num_deps;
> +	int i, r;
> +	struct drm_amdgpu_cs_chunk_sem *deps;
> +
> +	deps = (struct drm_amdgpu_cs_chunk_sem *)chunk->kdata;
> +	num_deps = chunk->length_dw * 4 /
> +		sizeof(struct drm_amdgpu_cs_chunk_sem);
> +
> +	for (i = 0; i < num_deps; ++i) {
> +		r = amdgpu_sem_lookup_and_signal(fpriv, deps[i].handle,
> +						 fence);
> +		if (r)
> +			return r;
> +	}
> +	return 0;
> +}
> +
> +static int amdgpu_cs_post_dependencies(struct amdgpu_cs_parser *p)
> +{
> +	int i, r;
> +
> +	for (i = 0; i < p->nchunks; ++i) {
> +		struct amdgpu_cs_chunk *chunk;
> +
> +		chunk = &p->chunks[i];
> +
> +		if (chunk->chunk_id == AMDGPU_CHUNK_ID_SEM_SIGNAL) {
> +			r = amdgpu_process_sem_signal_dep(p, chunk, p->fence);
> +			if (r)
> +				return r;
> +		}
> +	}
> +	return 0;
> +}
> +
>  static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>  			    union drm_amdgpu_cs *cs)
>  {
> @@ -1056,7 +1124,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>  	trace_amdgpu_cs_ioctl(job);
>  	amd_sched_entity_push_job(&job->base);
>  
> -	return 0;
> +	return amdgpu_cs_post_dependencies(p);
>  }
>  
>  int amdgpu_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> index 61d94c7..013aed1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> @@ -664,6 +664,8 @@ int amdgpu_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
>  	mutex_init(&fpriv->bo_list_lock);
>  	idr_init(&fpriv->bo_list_handles);
>  
> +	spin_lock_init(&fpriv->sem_handles_lock);
> +	idr_init(&fpriv->sem_handles);
>  	amdgpu_ctx_mgr_init(&fpriv->ctx_mgr);
>  
>  	file_priv->driver_priv = fpriv;
> @@ -689,6 +691,7 @@ void amdgpu_driver_postclose_kms(struct drm_device *dev,
>  	struct amdgpu_device *adev = dev->dev_private;
>  	struct amdgpu_fpriv *fpriv = file_priv->driver_priv;
>  	struct amdgpu_bo_list *list;
> +	struct amdgpu_sem *sem;
>  	int handle;
>  
>  	if (!fpriv)
> @@ -715,6 +718,10 @@ void amdgpu_driver_postclose_kms(struct drm_device *dev,
>  	idr_destroy(&fpriv->bo_list_handles);
>  	mutex_destroy(&fpriv->bo_list_lock);
>  
> +	idr_for_each_entry(&fpriv->sem_handles, sem, handle)
> +		amdgpu_sem_destroy(fpriv, handle);
> +	idr_destroy(&fpriv->sem_handles);
> +
>  	kfree(fpriv);
>  	file_priv->driver_priv = NULL;
>  
> @@ -896,6 +903,7 @@ const struct drm_ioctl_desc amdgpu_ioctls_kms[] = {
>  	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_VA, amdgpu_gem_va_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_OP, amdgpu_gem_op_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_USERPTR, amdgpu_gem_userptr_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(AMDGPU_SEM, amdgpu_sem_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>  };
>  const int amdgpu_max_kms_ioctl = ARRAY_SIZE(amdgpu_ioctls_kms);
>  
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sem.c
> new file mode 100644
> index 0000000..066520a
> --- /dev/null
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sem.c
> @@ -0,0 +1,204 @@
> +/*
> + * Copyright 2016 Advanced Micro Devices, Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + *
> + * Authors:
> + *    Chunming Zhou <david1.zhou@amd.com>
> + */
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/kernel.h>
> +#include <linux/poll.h>
> +#include <linux/seq_file.h>
> +#include <linux/export.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/uaccess.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/sync_file.h>
> +#include "amdgpu.h"
> +#include <drm/drmP.h>
> +
> +static inline struct sync_file *amdgpu_sync_file_lookup(struct amdgpu_fpriv *fpriv, u32 handle)
> +{
> +	struct sync_file *sync_file;
> +
> +	spin_lock(&fpriv->sem_handles_lock);
> +
> +	/* Check if we currently have a reference on the object */
> +	sync_file = idr_find(&fpriv->sem_handles, handle);
> +
> +	spin_unlock(&fpriv->sem_handles_lock);
> +
> +	return sync_file;
> +}
> +
> +static int amdgpu_sem_create(struct amdgpu_fpriv *fpriv, u32 *handle)
> +{
> +	struct sync_file *sync_file = sync_file_alloc();
> +	int ret;
> +
> +	if (!sync_file)
> +		return -ENOMEM;
> +
> +	snprintf(sync_file->name, sizeof(sync_file->name), "sync_sem");
> +
> +	/* we get a file reference and we use that in the idr. */
> +	idr_preload(GFP_KERNEL);
> +	spin_lock(&fpriv->sem_handles_lock);
> +
> +	ret = idr_alloc(&fpriv->sem_handles, sync_file, 1, 0, GFP_NOWAIT);
> +
> +	spin_unlock(&fpriv->sem_handles_lock);
> +	idr_preload_end();
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	*handle = ret;
> +	return 0;
> +}
> +
> +void amdgpu_sem_destroy(struct amdgpu_fpriv *fpriv, u32 handle)
> +{
> +	struct sync_file *sync_file = amdgpu_sync_file_lookup(fpriv, handle);
> +	if (!sync_file)
> +		return;
> +
> +	spin_lock(&fpriv->sem_handles_lock);
> +	idr_remove(&fpriv->sem_handles, handle);
> +	spin_unlock(&fpriv->sem_handles_lock);
> +
> +	fput(sync_file->file);
> +}
> +
> +
> +int amdgpu_sem_lookup_and_signal(struct amdgpu_fpriv *fpriv,
> +				 uint32_t handle,
> +				 struct dma_fence *fence)
> +{
> +	struct sync_file *sync_file;
> +	struct dma_fence *old_fence;
> +	sync_file = amdgpu_sync_file_lookup(fpriv, handle);
> +	if (!sync_file)
> +		return -EINVAL;
> +
> +	old_fence = sync_file_replace_fence(sync_file, fence);
> +	dma_fence_put(old_fence);
> +	return 0;
> +}
> +
> +static int amdgpu_sem_import(struct amdgpu_fpriv *fpriv,
> +				       int fd, u32 *handle)
> +{
> +	struct sync_file *sync_file = sync_file_fdget(fd);
> +	int ret;
> +
> +	if (!sync_file)
> +		return -EINVAL;
> +
> +	idr_preload(GFP_KERNEL);
> +	spin_lock(&fpriv->sem_handles_lock);
> +
> +	ret = idr_alloc(&fpriv->sem_handles, sync_file, 1, 0, GFP_NOWAIT);
> +
> +	spin_unlock(&fpriv->sem_handles_lock);
> +	idr_preload_end();
> +
> +	fput(sync_file->file);
> +	if (ret < 0)
> +		goto err_out;
> +
> +	*handle = ret;
> +	return 0;
> +err_out:
> +	return ret;
> +
> +}
> +
> +static int amdgpu_sem_export(struct amdgpu_fpriv *fpriv,
> +			     u32 handle, int *fd)
> +{
> +	struct sync_file *sync_file;
> +	int ret;
> +
> +	sync_file = amdgpu_sync_file_lookup(fpriv, handle);
> +	if (!sync_file)
> +		return -EINVAL;
> +
> +	ret = get_unused_fd_flags(O_CLOEXEC);
> +	if (ret < 0)
> +		goto err_put_file;
> +
> +	fd_install(ret, sync_file->file);
> +
> +	*fd = ret;
> +	return 0;
> +err_put_file:
> +	return ret;
> +}
> +
> +int amdgpu_sem_lookup_and_sync(struct amdgpu_device *adev,
> +			       struct amdgpu_fpriv *fpriv,
> +			       struct amdgpu_sync *sync,
> +			       uint32_t handle)
> +{
> +	int r;
> +	struct sync_file *sync_file;
> +	struct dma_fence *fence;
> +
> +	sync_file = amdgpu_sync_file_lookup(fpriv, handle);
> +	if (!sync_file)
> +		return -EINVAL;
> +
> +	fence = sync_file_replace_fence(sync_file, NULL);
> +	r = amdgpu_sync_fence(adev, sync, fence);
> +	dma_fence_put(fence);
> +
> +	return r;
> +}
> +
> +int amdgpu_sem_ioctl(struct drm_device *dev, void *data,
> +		     struct drm_file *filp)
> +{
> +	union drm_amdgpu_sem *args = data;
> +	struct amdgpu_fpriv *fpriv = filp->driver_priv;
> +	int r = 0;
> +
> +	switch (args->in.op) {
> +	case AMDGPU_SEM_OP_CREATE_SEM:
> +		r = amdgpu_sem_create(fpriv, &args->out.handle);
> +		break;
> +	case AMDGPU_SEM_OP_IMPORT_SEM:
> +		r = amdgpu_sem_import(fpriv, args->in.handle, &args->out.handle);
> +		break;
> +	case AMDGPU_SEM_OP_EXPORT_SEM:
> +		r = amdgpu_sem_export(fpriv, args->in.handle, &args->out.fd);
> +		break;
> +	case AMDGPU_SEM_OP_DESTROY_SEM:
> +		amdgpu_sem_destroy(fpriv, args->in.handle);
> +		break;
> +	default:
> +		r = -EINVAL;
> +		break;
> +	}
> +
> +	return r;
> +}
> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> index 5797283..646b103 100644
> --- a/include/uapi/drm/amdgpu_drm.h
> +++ b/include/uapi/drm/amdgpu_drm.h
> @@ -51,6 +51,7 @@ extern "C" {
>  #define DRM_AMDGPU_GEM_OP		0x10
>  #define DRM_AMDGPU_GEM_USERPTR		0x11
>  #define DRM_AMDGPU_WAIT_FENCES		0x12
> +#define DRM_AMDGPU_SEM                  0x13
>  
>  #define DRM_IOCTL_AMDGPU_GEM_CREATE	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_CREATE, union drm_amdgpu_gem_create)
>  #define DRM_IOCTL_AMDGPU_GEM_MMAP	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_MMAP, union drm_amdgpu_gem_mmap)
> @@ -65,6 +66,7 @@ extern "C" {
>  #define DRM_IOCTL_AMDGPU_GEM_OP		DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_OP, struct drm_amdgpu_gem_op)
>  #define DRM_IOCTL_AMDGPU_GEM_USERPTR	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_USERPTR, struct drm_amdgpu_gem_userptr)
>  #define DRM_IOCTL_AMDGPU_WAIT_FENCES	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_WAIT_FENCES, union drm_amdgpu_wait_fences)
> +#define DRM_IOCTL_AMDGPU_SEM		DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_SEM, union drm_amdgpu_sem)
>  
>  #define AMDGPU_GEM_DOMAIN_CPU		0x1
>  #define AMDGPU_GEM_DOMAIN_GTT		0x2
> @@ -335,6 +337,26 @@ union drm_amdgpu_wait_fences {
>  	struct drm_amdgpu_wait_fences_out out;
>  };
>  
> +#define AMDGPU_SEM_OP_CREATE_SEM 0
> +#define AMDGPU_SEM_OP_IMPORT_SEM 1
> +#define AMDGPU_SEM_OP_EXPORT_SEM 2
> +#define AMDGPU_SEM_OP_DESTROY_SEM 3
> +
> +struct drm_amdgpu_sem_in {
> +	__u32 op;
> +	__u32 handle;
> +};
> +
> +struct drm_amdgpu_sem_out {
> +	__u32 fd;
> +	__u32 handle;
> +};
> +
> +union drm_amdgpu_sem {
> +	struct drm_amdgpu_sem_in in;
> +	struct drm_amdgpu_sem_out out;
> +};
> +
>  #define AMDGPU_GEM_OP_GET_GEM_CREATE_INFO	0
>  #define AMDGPU_GEM_OP_SET_PLACEMENT		1
>  
> @@ -390,6 +412,8 @@ struct drm_amdgpu_gem_va {
>  #define AMDGPU_CHUNK_ID_IB		0x01
>  #define AMDGPU_CHUNK_ID_FENCE		0x02
>  #define AMDGPU_CHUNK_ID_DEPENDENCIES	0x03
> +#define AMDGPU_CHUNK_ID_SEM_WAIT        0x04
> +#define AMDGPU_CHUNK_ID_SEM_SIGNAL      0x05
>  
>  struct drm_amdgpu_cs_chunk {
>  	__u32		chunk_id;
> @@ -454,6 +478,10 @@ struct drm_amdgpu_cs_chunk_fence {
>  	__u32 offset;
>  };
>  
> +struct drm_amdgpu_cs_chunk_sem {
> +	__u32 handle;
> +};
> +
>  struct drm_amdgpu_cs_chunk_data {
>  	union {
>  		struct drm_amdgpu_cs_chunk_ib		ib_data;
> -- 
> 2.7.4
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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