Re: [PATCH 3/5] dma-buf: add dma_fence_chain_alloc/free v2

Fri, 11 Jun 2021 07:54:55 -0700 



Am 11.06.21 um 16:52 schrieb Daniel Vetter:

On Fri, Jun 11, 2021 at 02:02:59PM +0200, Christian König wrote:

Add a common allocation helper. Cleaning up the mix of kzalloc/kmalloc
and some unused code in the selftest.

v2: polish kernel doc a bit

Signed-off-by: Christian König <christian.koe...@amd.com>
Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>

Given how absolutely wrong I was I'm not sure this r-b here is justified
:-)



Ups, that was also not added intentionally. It's just to hot in my flat 
and to few hours till the weekend.





---
  drivers/dma-buf/st-dma-fence-chain.c          | 16 ++++---------
  drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c        |  4 ++--
  drivers/gpu/drm/drm_syncobj.c                 |  6 ++---
  .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |  6 ++---
  drivers/gpu/drm/msm/msm_gem_submit.c          |  6 ++---
  include/linux/dma-fence-chain.h               | 23 +++++++++++++++++++
  6 files changed, 36 insertions(+), 25 deletions(-)

diff --git a/drivers/dma-buf/st-dma-fence-chain.c 
b/drivers/dma-buf/st-dma-fence-chain.c
index 9525f7f56119..8ce1ea59d31b 100644
--- a/drivers/dma-buf/st-dma-fence-chain.c
+++ b/drivers/dma-buf/st-dma-fence-chain.c
@@ -58,28 +58,20 @@ static struct dma_fence *mock_fence(void)
        return &f->base;
  }

  
-static inline struct mock_chain {

-       struct dma_fence_chain base;
-} *to_mock_chain(struct dma_fence *f) {
-       return container_of(f, struct mock_chain, base.base);
-}
-
  static struct dma_fence *mock_chain(struct dma_fence *prev,
                                    struct dma_fence *fence,
                                    u64 seqno)
  {
-       struct mock_chain *f;
+       struct dma_fence_chain *f;

  
-	f = kmalloc(sizeof(*f), GFP_KERNEL);

+       f = dma_fence_chain_alloc();
        if (!f)
                return NULL;

  
-	dma_fence_chain_init(&f->base,

-                            dma_fence_get(prev),
-                            dma_fence_get(fence),
+       dma_fence_chain_init(f, dma_fence_get(prev), dma_fence_get(fence),
                             seqno);

  
-	return &f->base.base;

+       return &f->base;
  }

  
  static int sanitycheck(void *arg)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 90136f9dedd6..325e82621467 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1124,7 +1124,7 @@ static int 
amdgpu_cs_process_syncobj_timeline_out_dep(struct amdgpu_cs_parser *p

  
  		dep->chain = NULL;

                if (syncobj_deps[i].point) {
-                       dep->chain = kmalloc(sizeof(*dep->chain), GFP_KERNEL);
+                       dep->chain = dma_fence_chain_alloc();
                        if (!dep->chain)
                                return -ENOMEM;
                }
@@ -1132,7 +1132,7 @@ static int 
amdgpu_cs_process_syncobj_timeline_out_dep(struct amdgpu_cs_parser *p
                dep->syncobj = drm_syncobj_find(p->filp,
                                                syncobj_deps[i].handle);
                if (!dep->syncobj) {
-                       kfree(dep->chain);
+                       dma_fence_chain_free(dep->chain);
                        return -EINVAL;
                }
                dep->point = syncobj_deps[i].point;
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index fdd2ec87cdd1..1c5b9ef6da37 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -861,7 +861,7 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file 
*file_private,
                                     &fence);
        if (ret)
                goto err;
-       chain = kzalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
+       chain = dma_fence_chain_alloc();
        if (!chain) {
                ret = -ENOMEM;
                goto err1;
@@ -1402,10 +1402,10 @@ drm_syncobj_timeline_signal_ioctl(struct drm_device 
*dev, void *data,
                goto err_points;
        }
        for (i = 0; i < args->count_handles; i++) {
-               chains[i] = kzalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
+               chains[i] = dma_fence_chain_alloc();
                if (!chains[i]) {
                        for (j = 0; j < i; j++)
-                               kfree(chains[j]);
+                               dma_fence_chain_free(chains[j]);
                        ret = -ENOMEM;
                        goto err_chains;
                }
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 66789111a24b..a22cb86730b3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2983,7 +2983,7 @@ __free_fence_array(struct eb_fence *fences, unsigned int 
n)
        while (n--) {
                drm_syncobj_put(ptr_mask_bits(fences[n].syncobj, 2));
                dma_fence_put(fences[n].dma_fence);
-               kfree(fences[n].chain_fence);
+               dma_fence_chain_free(fences[n].chain_fence);
        }
        kvfree(fences);
  }
@@ -3097,9 +3097,7 @@ add_timeline_fence_array(struct i915_execbuffer *eb,
                                return -EINVAL;
                        }

  
-			f->chain_fence =

-                               kmalloc(sizeof(*f->chain_fence),
-                                       GFP_KERNEL);
+                       f->chain_fence = dma_fence_chain_alloc();
                        if (!f->chain_fence) {
                                drm_syncobj_put(syncobj);
                                dma_fence_put(fence);
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c 
b/drivers/gpu/drm/msm/msm_gem_submit.c
index 5480852bdeda..6ff6df6c4791 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -586,9 +586,7 @@ static struct msm_submit_post_dep 
*msm_parse_post_deps(struct drm_device *dev,
                                break;
                        }

  
-			post_deps[i].chain =

-                               kmalloc(sizeof(*post_deps[i].chain),
-                                       GFP_KERNEL);
+                       post_deps[i].chain = dma_fence_chain_alloc();
                        if (!post_deps[i].chain) {
                                ret = -ENOMEM;
                                break;
@@ -605,7 +603,7 @@ static struct msm_submit_post_dep 
*msm_parse_post_deps(struct drm_device *dev,

  
  	if (ret) {

                for (j = 0; j <= i; ++j) {
-                       kfree(post_deps[j].chain);
+                       dma_fence_chain_free(post_deps[j].chain);
                        if (post_deps[j].syncobj)
                                drm_syncobj_put(post_deps[j].syncobj);
                }
diff --git a/include/linux/dma-fence-chain.h b/include/linux/dma-fence-chain.h
index c6eb3aa45668..7ec36d850363 100644
--- a/include/linux/dma-fence-chain.h
+++ b/include/linux/dma-fence-chain.h
@@ -12,6 +12,7 @@

  
  #include <linux/dma-fence.h>

  #include <linux/irq_work.h>
+#include <linux/slab.h>

  
  /**

   * struct dma_fence_chain - fence to represent an node of a fence chain
@@ -66,6 +67,28 @@ to_dma_fence_chain(struct dma_fence *fence)
        return container_of(fence, struct dma_fence_chain, base);
  }

  
+/**

+ * dma_fence_chain_alloc
+ *
+ * Returns a new dma_fence_chain object or NULL on failure.

                struct dma_fence_chain for that hyperlink goodness


+ */
+static inline struct dma_fence_chain *dma_fence_chain_alloc(void)
+{
+       return kmalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
+};
+
+/**
+ * dma_fence_chain_free
+ * @chain: chain node to free
+ *
+ * Frees up an allocated but not used dma_fence_chain node. This doesn't need

Same here.


+ * an RCU grace period since the fence was never initialized nor published.

I'd add even more clarification, like:

"After dma_fence_chain_init() has been called the fence must be released
by calling dma_fence_put(), and not through this function."

That's still a notch too strict (in theory as long as the fence isn't
published anywhere it's all fine), but it keeps the door open for some
validation.

With the doc polish:

Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>


Thanks,
Christian.





+ */
+static inline void dma_fence_chain_free(struct dma_fence_chain *chain)
+{
+       kfree(chain);
+};
+
  /**
   * dma_fence_chain_for_each - iterate over all fences in chain
   * @iter: current fence
--
2.25.1

























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